diff --git a/.github/workflows/CICD.yml b/.github/workflows/CICD.yml
index 42c448561..a8ed1b704 100644
--- a/.github/workflows/CICD.yml
+++ b/.github/workflows/CICD.yml
@@ -5,7 +5,7 @@ name: CICD
 # spell-checker:ignore (jargon) SHAs deps softprops toolchain
 # spell-checker:ignore (names) CodeCOV MacOS MinGW Peltoche rivy
 # spell-checker:ignore (shell/tools) choco clippy dmake dpkg esac fakeroot gmake grcov halium lcov libssl mkdir popd printf pushd rustc rustfmt rustup shopt xargs
-# spell-checker:ignore (misc) aarch alnum armhf bindir busytest coreutils gnueabihf issuecomment maint nullglob onexitbegin onexitend tempfile testsuite uutils
+# spell-checker:ignore (misc) aarch alnum armhf bindir busytest coreutils gnueabihf issuecomment maint nullglob onexitbegin onexitend runtest tempfile testsuite uutils
 
 env:
   PROJECT_NAME: coreutils
@@ -32,12 +32,12 @@ jobs:
       shell: bash
       run: |
         ## VARs setup
+        outputs() { for var in "$@" ; do echo steps.vars.outputs.${var}="${!var}"; echo ::set-output name=${var}::${!var}; done; }
         # target-specific options
         # * CARGO_FEATURES_OPTION
         CARGO_FEATURES_OPTION='' ;
         if [ -n "${{ matrix.job.features }}" ]; then CARGO_FEATURES_OPTION='--features "${{ matrix.job.features }}"' ; fi
-        echo set-output name=CARGO_FEATURES_OPTION::${CARGO_FEATURES_OPTION}
-        echo ::set-output name=CARGO_FEATURES_OPTION::${CARGO_FEATURES_OPTION}
+        outputs CARGO_FEATURES_OPTION
     - name: Install `rust` toolchain
       uses: actions-rs/toolchain@v1
       with:
@@ -93,12 +93,12 @@ jobs:
       shell: bash
       run: |
         ## VARs setup
+        outputs() { for var in "$@" ; do echo steps.vars.outputs.${var}="${!var}"; echo ::set-output name=${var}::${!var}; done; }
         # target-specific options
         # * CARGO_FEATURES_OPTION
         CARGO_FEATURES_OPTION='' ;
         if [ -n "${{ matrix.job.features }}" ]; then CARGO_FEATURES_OPTION='--features "${{ matrix.job.features }}"' ; fi
-        echo set-output name=CARGO_FEATURES_OPTION::${CARGO_FEATURES_OPTION}
-        echo ::set-output name=CARGO_FEATURES_OPTION::${CARGO_FEATURES_OPTION}
+        outputs CARGO_FEATURES_OPTION
     - name: Install `rust` toolchain
       uses: actions-rs/toolchain@v1
       with:
@@ -197,7 +197,11 @@ jobs:
       run: |
         bindir=$(pwd)/target/debug
         cd tmp/busybox-*/testsuite
-        S=$(bindir=$bindir ./runtest) && printf "%s\n" "$S" || { printf "%s\n" "$S" | grep "FAIL:" | sed -e "s/FAIL: /::warning ::Test failure:/g" ; }
+        ## S=$(bindir=$bindir ./runtest) && printf "%s\n" "$S" || { printf "%s\n" "$S" | grep "FAIL:" | sed -e "s/FAIL: /::warning ::Test failure:/g" ; }
+        output=$(bindir=$bindir ./runtest 2>&1 || true)
+        printf "%s\n" "${output}"
+        n_fails=$(echo "$output" | grep "^FAIL:\s" | wc --lines)
+        if [ $n_fails -gt 0 ] ; then echo "::warning ::${n_fails}+ test failures" ; fi
 
   makefile_build:
     name: Test the build target of the Makefile
@@ -261,22 +265,20 @@ jobs:
       shell: bash
       run: |
         ## VARs setup
+        outputs() { for var in "$@" ; do echo steps.vars.outputs.${var}="${!var}"; echo ::set-output name=${var}::${!var}; done; }
         # toolchain
         TOOLCHAIN="stable" ## default to "stable" toolchain
         # * specify alternate/non-default TOOLCHAIN for *-pc-windows-gnu targets; gnu targets on Windows are broken for the standard *-pc-windows-msvc toolchain (refs: GH:rust-lang/rust#47048, GH:rust-lang/rust#53454, GH:rust-lang/cargo#6754)
         case ${{ matrix.job.target }} in *-pc-windows-gnu) TOOLCHAIN="stable-${{ matrix.job.target }}" ;; esac;
         # * use requested TOOLCHAIN if specified
         if [ -n "${{ matrix.job.toolchain }}" ]; then TOOLCHAIN="${{ matrix.job.toolchain }}" ; fi
-        echo set-output name=TOOLCHAIN::${TOOLCHAIN:-<empty>/false}
-        echo ::set-output name=TOOLCHAIN::${TOOLCHAIN}
+        outputs TOOLCHAIN
         # staging directory
         STAGING='_staging'
-        echo set-output name=STAGING::${STAGING}
-        echo ::set-output name=STAGING::${STAGING}
+        outputs STAGING
         # determine EXE suffix
         EXE_suffix="" ; case '${{ matrix.job.target }}' in *-pc-windows-*) EXE_suffix=".exe" ;; esac;
-        echo set-output name=EXE_suffix::${EXE_suffix}
-        echo ::set-output name=EXE_suffix::${EXE_suffix}
+        outputs EXE_suffix
         # parse commit reference info
         echo GITHUB_REF=${GITHUB_REF}
         echo GITHUB_SHA=${GITHUB_SHA}
@@ -284,14 +286,7 @@ jobs:
         unset REF_BRANCH ; case "${GITHUB_REF}" in refs/heads/*) REF_BRANCH=${GITHUB_REF#refs/heads/} ;; esac;
         unset REF_TAG ; case "${GITHUB_REF}" in refs/tags/*) REF_TAG=${GITHUB_REF#refs/tags/} ;; esac;
         REF_SHAS=${GITHUB_SHA:0:8}
-        echo set-output name=REF_NAME::${REF_NAME}
-        echo set-output name=REF_BRANCH::${REF_BRANCH}
-        echo set-output name=REF_TAG::${REF_TAG}
-        echo set-output name=REF_SHAS::${REF_SHAS}
-        echo ::set-output name=REF_NAME::${REF_NAME}
-        echo ::set-output name=REF_BRANCH::${REF_BRANCH}
-        echo ::set-output name=REF_TAG::${REF_TAG}
-        echo ::set-output name=REF_SHAS::${REF_SHAS}
+        outputs REF_NAME REF_BRANCH REF_TAG REF_SHAS
         # parse target
         unset TARGET_ARCH
         case '${{ matrix.job.target }}' in
@@ -301,68 +296,50 @@ jobs:
           i686-*) TARGET_ARCH=i686 ;;
           x86_64-*) TARGET_ARCH=x86_64 ;;
         esac;
-        echo set-output name=TARGET_ARCH::${TARGET_ARCH}
-        echo ::set-output name=TARGET_ARCH::${TARGET_ARCH}
         unset TARGET_OS ; case '${{ matrix.job.target }}' in *-linux-*) TARGET_OS=linux ;; *-apple-*) TARGET_OS=macos ;; *-windows-*) TARGET_OS=windows ;; esac;
-        echo set-output name=TARGET_OS::${TARGET_OS}
-        echo ::set-output name=TARGET_OS::${TARGET_OS}
+        outputs TARGET_ARCH TARGET_OS
         # package name
         PKG_suffix=".tar.gz" ; case '${{ matrix.job.target }}' in *-pc-windows-*) PKG_suffix=".zip" ;; esac;
         PKG_BASENAME=${PROJECT_NAME}-${REF_TAG:-$REF_SHAS}-${{ matrix.job.target }}
         PKG_NAME=${PKG_BASENAME}${PKG_suffix}
-        echo set-output name=PKG_suffix::${PKG_suffix}
-        echo set-output name=PKG_BASENAME::${PKG_BASENAME}
-        echo set-output name=PKG_NAME::${PKG_NAME}
-        echo ::set-output name=PKG_suffix::${PKG_suffix}
-        echo ::set-output name=PKG_BASENAME::${PKG_BASENAME}
-        echo ::set-output name=PKG_NAME::${PKG_NAME}
+        outputs PKG_suffix PKG_BASENAME PKG_NAME
         # deployable tag? (ie, leading "vM" or "M"; M == version number)
         unset DEPLOY ; if [[ $REF_TAG =~ ^[vV]?[0-9].* ]]; then DEPLOY='true' ; fi
-        echo set-output name=DEPLOY::${DEPLOY:-<empty>/false}
-        echo ::set-output name=DEPLOY::${DEPLOY}
+        outputs DEPLOY
         # DPKG architecture?
         unset DPKG_ARCH
         case ${{ matrix.job.target }} in
           x86_64-*-linux-*) DPKG_ARCH=amd64 ;;
           *-linux-*) DPKG_ARCH=${TARGET_ARCH} ;;
         esac
-        echo set-output name=DPKG_ARCH::${DPKG_ARCH}
-        echo ::set-output name=DPKG_ARCH::${DPKG_ARCH}
+        outputs DPKG_ARCH
         # DPKG version?
         unset DPKG_VERSION ; if [[ $REF_TAG =~ ^[vV]?[0-9].* ]]; then DPKG_VERSION=${REF_TAG/#[vV]/} ; fi
-        echo set-output name=DPKG_VERSION::${DPKG_VERSION}
-        echo ::set-output name=DPKG_VERSION::${DPKG_VERSION}
+        outputs DPKG_VERSION
         # DPKG base name/conflicts?
         DPKG_BASENAME=${PROJECT_NAME}
         DPKG_CONFLICTS=${PROJECT_NAME}-musl
         case ${{ matrix.job.target }} in *-musl) DPKG_BASENAME=${PROJECT_NAME}-musl ; DPKG_CONFLICTS=${PROJECT_NAME} ;; esac;
-        echo set-output name=DPKG_BASENAME::${DPKG_BASENAME}
-        echo set-output name=DPKG_CONFLICTS::${DPKG_CONFLICTS}
-        echo ::set-output name=DPKG_BASENAME::${DPKG_BASENAME}
-        echo ::set-output name=DPKG_CONFLICTS::${DPKG_CONFLICTS}
+        outputs DPKG_BASENAME DPKG_CONFLICTS
         # DPKG name
         unset DPKG_NAME;
         if [[ -n $DPKG_ARCH && -n $DPKG_VERSION ]]; then DPKG_NAME="${DPKG_BASENAME}_${DPKG_VERSION}_${DPKG_ARCH}.deb" ; fi
-        echo set-output name=DPKG_NAME::${DPKG_NAME}
-        echo ::set-output name=DPKG_NAME::${DPKG_NAME}
+        outputs DPKG_NAME
         # target-specific options
         # * CARGO_FEATURES_OPTION
         CARGO_FEATURES_OPTION='' ;
         if [ -n "${{ matrix.job.features }}" ]; then CARGO_FEATURES_OPTION='--features "${{ matrix.job.features }}"' ; fi
-        echo set-output name=CARGO_FEATURES_OPTION::${CARGO_FEATURES_OPTION}
-        echo ::set-output name=CARGO_FEATURES_OPTION::${CARGO_FEATURES_OPTION}
+        outputs CARGO_FEATURES_OPTION
         # * CARGO_USE_CROSS (truthy)
         CARGO_USE_CROSS='true' ; case '${{ matrix.job.use-cross }}' in ''|0|f|false|n|no) unset CARGO_USE_CROSS ;; esac;
-        echo set-output name=CARGO_USE_CROSS::${CARGO_USE_CROSS:-<empty>/false}
-        echo ::set-output name=CARGO_USE_CROSS::${CARGO_USE_CROSS}
+        outputs CARGO_USE_CROSS
         # ** pass needed environment into `cross` container (iff `cross` not already configured via "Cross.toml")
         if [ -n "${CARGO_USE_CROSS}" ] && [ ! -e "Cross.toml" ] ; then
           printf "[build.env]\npassthrough = [\"CI\"]\n" > Cross.toml
         fi
         # * test only library and/or binaries for arm-type targets
         unset CARGO_TEST_OPTIONS ; case '${{ matrix.job.target }}' in aarch64-* | arm-*) CARGO_TEST_OPTIONS="--bins" ;; esac;
-        echo set-output name=CARGO_TEST_OPTIONS::${CARGO_TEST_OPTIONS}
-        echo ::set-output name=CARGO_TEST_OPTIONS::${CARGO_TEST_OPTIONS}
+        outputs CARGO_TEST_OPTIONS
         # * executable for `strip`?
         STRIP="strip"
         case ${{ matrix.job.target }} in
@@ -370,8 +347,7 @@ jobs:
           arm-*-linux-gnueabihf) STRIP="arm-linux-gnueabihf-strip" ;;
           *-pc-windows-msvc) STRIP="" ;;
         esac;
-        echo set-output name=STRIP::${STRIP:-<empty>/false}
-        echo ::set-output name=STRIP::${STRIP}
+        outputs STRIP
     - name: Create all needed build/work directories
       shell: bash
       run: |
@@ -395,11 +371,12 @@ jobs:
       shell: bash
       run: |
         ## Dependent VARs setup
+        outputs() { for var in "$@" ; do echo steps.vars.outputs.${var}="${!var}"; echo ::set-output name=${var}::${!var}; done; }
         # * determine sub-crate utility list
         UTILITY_LIST="$(./util/show-utils.sh ${CARGO_FEATURES_OPTION})"
+        echo UTILITY_LIST=${UTILITY_LIST}
         CARGO_UTILITY_LIST_OPTIONS="$(for u in ${UTILITY_LIST}; do echo "-puu_${u}"; done;)"
-        echo set-output name=UTILITY_LIST::${UTILITY_LIST}
-        echo ::set-output name=CARGO_UTILITY_LIST_OPTIONS::${CARGO_UTILITY_LIST_OPTIONS}
+        outputs CARGO_UTILITY_LIST_OPTIONS
     - name: Install `cargo-tree` # for dependency information
       uses: actions-rs/install@v0.1
       with:
@@ -524,34 +501,31 @@ jobs:
       id: vars
       shell: bash
       run: |
+        ## VARs setup
+        outputs() { for var in "$@" ; do echo steps.vars.outputs.${var}="${!var}"; echo ::set-output name=${var}::${!var}; done; }
         # toolchain
         TOOLCHAIN="nightly-${{ env.RUST_COV_SRV }}" ## default to "nightly" toolchain (required for certain required unstable compiler flags) ## !maint: refactor when stable channel has needed support
         # * specify gnu-type TOOLCHAIN for windows; `grcov` requires gnu-style code coverage data files
         case ${{ matrix.job.os }} in windows-*) TOOLCHAIN="$TOOLCHAIN-x86_64-pc-windows-gnu" ;; esac;
         # * use requested TOOLCHAIN if specified
         if [ -n "${{ matrix.job.toolchain }}" ]; then TOOLCHAIN="${{ matrix.job.toolchain }}" ; fi
-        echo set-output name=TOOLCHAIN::${TOOLCHAIN}
-        echo ::set-output name=TOOLCHAIN::${TOOLCHAIN}
+        outputs TOOLCHAIN
         # staging directory
         STAGING='_staging'
-        echo set-output name=STAGING::${STAGING}
-        echo ::set-output name=STAGING::${STAGING}
+        outputs STAGING
         ## # check for CODECOV_TOKEN availability (work-around for inaccessible 'secrets' object for 'if'; see <https://github.community/t5/GitHub-Actions/jobs-lt-job-id-gt-if-does-not-work-with-env-secrets/m-p/38549>)
         ## # note: CODECOV_TOKEN / HAS_CODECOV_TOKEN is not needed for public repositories when using AppVeyor, Azure Pipelines, CircleCI, GitHub Actions, Travis (see <https://docs.codecov.io/docs/about-the-codecov-bash-uploader#section-upload-token>)
         ## unset HAS_CODECOV_TOKEN
         ## if [ -n $CODECOV_TOKEN ]; then HAS_CODECOV_TOKEN='true' ; fi
-        ## echo set-output name=HAS_CODECOV_TOKEN::${HAS_CODECOV_TOKEN}
-        ## echo ::set-output name=HAS_CODECOV_TOKEN::${HAS_CODECOV_TOKEN}
+        ## outputs HAS_CODECOV_TOKEN
         # target-specific options
         # * CARGO_FEATURES_OPTION
         CARGO_FEATURES_OPTION='--all-features' ;  ## default to '--all-features' for code coverage
         if [ -n "${{ matrix.job.features }}" ]; then CARGO_FEATURES_OPTION='--features "${{ matrix.job.features }}"' ; fi
-        echo set-output name=CARGO_FEATURES_OPTION::${CARGO_FEATURES_OPTION}
-        echo ::set-output name=CARGO_FEATURES_OPTION::${CARGO_FEATURES_OPTION}
+        outputs CARGO_FEATURES_OPTION
         # * CODECOV_FLAGS
         CODECOV_FLAGS=$( echo "${{ matrix.job.os }}" | sed 's/[^[:alnum:]]/_/g' )
-        echo set-output name=CODECOV_FLAGS::${CODECOV_FLAGS}
-        echo ::set-output name=CODECOV_FLAGS::${CODECOV_FLAGS}
+        outputs CODECOV_FLAGS
     - name: rust toolchain ~ install
       uses: actions-rs/toolchain@v1
       with:
@@ -563,12 +537,11 @@ jobs:
       shell: bash
       run: |
         ## Dependent VARs setup
+        outputs() { for var in "$@" ; do echo steps.vars.outputs.${var}="${!var}"; echo ::set-output name=${var}::${!var}; done; }
         # * determine sub-crate utility list
-        # UTILITY_LIST="$(./util/show-utils.sh ${CARGO_FEATURES_OPTION})"
-        UTILITY_LIST="id" # TODO: remove after debugging
+        UTILITY_LIST="$(./util/show-utils.sh ${CARGO_FEATURES_OPTION})"
         CARGO_UTILITY_LIST_OPTIONS="$(for u in ${UTILITY_LIST}; do echo "-puu_${u}"; done;)"
-        echo set-output name=UTILITY_LIST::${UTILITY_LIST}
-        echo ::set-output name=CARGO_UTILITY_LIST_OPTIONS::${CARGO_UTILITY_LIST_OPTIONS}
+        outputs CARGO_UTILITY_LIST_OPTIONS
     - name: Test uucore
       uses: actions-rs/cargo@v1
       with:
@@ -607,7 +580,7 @@ jobs:
       with:
         crate: grcov
         version: latest
-        use-tool-cache: true
+        use-tool-cache: false
     - name: Generate coverage data (via `grcov`)
       id: coverage
       shell: bash
diff --git a/.vscode/cspell.dictionaries/people.wordlist.txt b/.vscode/cspell.dictionaries/people.wordlist.txt
index 01cfa4a3e..0a091633f 100644
--- a/.vscode/cspell.dictionaries/people.wordlist.txt
+++ b/.vscode/cspell.dictionaries/people.wordlist.txt
@@ -97,6 +97,9 @@ Michael Debertol
 Michael Gehring
     Michael
     Gehring
+Mitchell Mebane
+    Mitchell
+    Mebane
 Morten Olsen Lysgaard
     Morten
     Olsen
diff --git a/.vscode/cspell.dictionaries/workspace.wordlist.txt b/.vscode/cspell.dictionaries/workspace.wordlist.txt
index e2a864f9c..ed634dffb 100644
--- a/.vscode/cspell.dictionaries/workspace.wordlist.txt
+++ b/.vscode/cspell.dictionaries/workspace.wordlist.txt
@@ -7,6 +7,7 @@ advapi
 advapi32-sys
 aho-corasick
 backtrace
+blake2b_simd
 bstr
 byteorder
 chacha
@@ -47,6 +48,7 @@ xattr
 # * rust/rustc
 RUSTDOCFLAGS
 RUSTFLAGS
+bitor # BitOr trait function
 bitxor # BitXor trait function
 clippy
 concat
diff --git a/Cargo.lock b/Cargo.lock
index 43d491cef..089d30554 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -6,16 +6,6 @@ version = "0.11.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "fe438c63458706e03479442743baae6c88256498e6431708f6dfc520a26515d3"
 
-[[package]]
-name = "advapi32-sys"
-version = "0.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e06588080cb19d0acb6739808aafa5f26bfb2ca015b2b6370028b44cf7cb8a9a"
-dependencies = [
- "winapi 0.2.8",
- "winapi-build",
-]
-
 [[package]]
 name = "aho-corasick"
 version = "0.7.18"
@@ -1772,6 +1762,7 @@ dependencies = [
 name = "uu_cat"
 version = "0.0.6"
 dependencies = [
+ "atty",
  "clap",
  "nix 0.20.0",
  "thiserror",
@@ -1784,6 +1775,7 @@ dependencies = [
 name = "uu_chgrp"
 version = "0.0.6"
 dependencies = [
+ "clap",
  "uucore",
  "uucore_procs",
  "walkdir",
@@ -1872,6 +1864,7 @@ dependencies = [
 name = "uu_cut"
 version = "0.0.6"
 dependencies = [
+ "atty",
  "bstr",
  "clap",
  "memchr 2.4.0",
@@ -2262,6 +2255,7 @@ dependencies = [
 name = "uu_nohup"
 version = "0.0.6"
 dependencies = [
+ "atty",
  "clap",
  "libc",
  "uucore",
@@ -2420,6 +2414,7 @@ dependencies = [
  "uucore",
  "uucore_procs",
  "walkdir",
+ "winapi 0.3.9",
 ]
 
 [[package]]
@@ -2601,7 +2596,6 @@ name = "uu_timeout"
 version = "0.0.6"
 dependencies = [
  "clap",
- "getopts",
  "libc",
  "uucore",
  "uucore_procs",
@@ -2659,6 +2653,7 @@ dependencies = [
 name = "uu_tty"
 version = "0.0.6"
 dependencies = [
+ "atty",
  "clap",
  "libc",
  "uucore",
@@ -2750,7 +2745,6 @@ dependencies = [
 name = "uu_whoami"
 version = "0.0.6"
 dependencies = [
- "advapi32-sys",
  "clap",
  "uucore",
  "uucore_procs",
diff --git a/Cargo.toml b/Cargo.toml
index 19ebca511..804c5f978 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -351,7 +351,7 @@ time = "0.1"
 unindent = "0.1"
 uucore = { version=">=0.0.8", package="uucore", path="src/uucore", features=["entries", "process"] }
 walkdir = "2.2"
-atty = "0.2.14"
+atty = "0.2"
 
 [target.'cfg(unix)'.dev-dependencies]
 rlimit = "0.4.0"
diff --git a/GNUmakefile b/GNUmakefile
index 102856b66..e5ad01340 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -268,11 +268,11 @@ test:
 	${CARGO} test ${CARGOFLAGS} --features "$(TESTS) $(TEST_SPEC_FEATURE)" --no-default-features $(TEST_NO_FAIL_FAST)
 
 busybox-src:
-	if [ ! -e $(BUSYBOX_SRC) ]; then \
-	mkdir -p $(BUSYBOX_ROOT); \
-	wget https://busybox.net/downloads/busybox-$(BUSYBOX_VER).tar.bz2 -P $(BUSYBOX_ROOT); \
-	tar -C $(BUSYBOX_ROOT) -xf $(BUSYBOX_ROOT)/busybox-$(BUSYBOX_VER).tar.bz2; \
-	fi; \
+	if [ ! -e "$(BUSYBOX_SRC)" ] ; then \
+		mkdir -p "$(BUSYBOX_ROOT)" ; \
+		wget "https://busybox.net/downloads/busybox-$(BUSYBOX_VER).tar.bz2" -P "$(BUSYBOX_ROOT)" ; \
+		tar -C "$(BUSYBOX_ROOT)" -xf "$(BUSYBOX_ROOT)/busybox-$(BUSYBOX_VER).tar.bz2" ; \
+	fi ;
 
 # This is a busybox-specific config file their test suite wants to parse.
 $(BUILDDIR)/.config: $(BASEDIR)/.busybox-config
@@ -280,10 +280,12 @@ $(BUILDDIR)/.config: $(BASEDIR)/.busybox-config
 
 # Test under the busybox test suite
 $(BUILDDIR)/busybox: busybox-src build-coreutils $(BUILDDIR)/.config
-	cp $(BUILDDIR)/coreutils $(BUILDDIR)/busybox; \
-	chmod +x $@;
+	cp "$(BUILDDIR)/coreutils" "$(BUILDDIR)/busybox"
+	chmod +x $@
 
 prepare-busytest: $(BUILDDIR)/busybox
+	# disable inapplicable tests
+	-( cd "$(BUSYBOX_SRC)/testsuite" ; if [ -e "busybox.tests" ] ; then mv busybox.tests busybox.tests- ; fi ; )
 
 ifeq ($(EXES),)
 busytest:
diff --git a/src/uu/base32/src/base32.rs b/src/uu/base32/src/base32.rs
index f0e187c31..e6a01cb34 100644
--- a/src/uu/base32/src/base32.rs
+++ b/src/uu/base32/src/base32.rs
@@ -38,18 +38,11 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
 
     let config_result: Result<base_common::Config, String> =
         base_common::parse_base_cmd_args(args, name, VERSION, ABOUT, &usage);
-
-    if config_result.is_err() {
-        match config_result {
-            Ok(_) => panic!(),
-            Err(s) => crash!(BASE_CMD_PARSE_ERROR, "{}", s),
-        }
-    }
+    let config = config_result.unwrap_or_else(|s| crash!(BASE_CMD_PARSE_ERROR, "{}", s));
 
     // Create a reference to stdin so we can return a locked stdin from
     // parse_base_cmd_args
     let stdin_raw = stdin();
-    let config = config_result.unwrap();
     let mut input: Box<dyn Read> = base_common::get_input(&config, &stdin_raw);
 
     base_common::handle_input(
diff --git a/src/uu/base32/src/base_common.rs b/src/uu/base32/src/base_common.rs
index ee5fe8675..256b674e2 100644
--- a/src/uu/base32/src/base_common.rs
+++ b/src/uu/base32/src/base_common.rs
@@ -54,15 +54,13 @@ impl Config {
             None => None,
         };
 
-        let cols = match options.value_of(options::WRAP) {
-            Some(num) => match num.parse::<usize>() {
-                Ok(n) => Some(n),
-                Err(e) => {
-                    return Err(format!("Invalid wrap size: ‘{}’: {}", num, e));
-                }
-            },
-            None => None,
-        };
+        let cols = options
+            .value_of(options::WRAP)
+            .map(|num| {
+                num.parse::<usize>()
+                    .map_err(|e| format!("Invalid wrap size: ‘{}’: {}", num, e))
+            })
+            .transpose()?;
 
         Ok(Config {
             decode: options.is_present(options::DECODE),
diff --git a/src/uu/base64/src/base64.rs b/src/uu/base64/src/base64.rs
index 810df4fe8..0dd831027 100644
--- a/src/uu/base64/src/base64.rs
+++ b/src/uu/base64/src/base64.rs
@@ -38,18 +38,11 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
     let name = executable!();
     let config_result: Result<base_common::Config, String> =
         base_common::parse_base_cmd_args(args, name, VERSION, ABOUT, &usage);
-
-    if config_result.is_err() {
-        match config_result {
-            Ok(_) => panic!(),
-            Err(s) => crash!(BASE_CMD_PARSE_ERROR, "{}", s),
-        }
-    }
+    let config = config_result.unwrap_or_else(|s| crash!(BASE_CMD_PARSE_ERROR, "{}", s));
 
     // Create a reference to stdin so we can return a locked stdin from
     // parse_base_cmd_args
     let stdin_raw = stdin();
-    let config = config_result.unwrap();
     let mut input: Box<dyn Read> = base_common::get_input(&config, &stdin_raw);
 
     base_common::handle_input(
diff --git a/src/uu/basename/src/basename.rs b/src/uu/basename/src/basename.rs
index a0eed93f1..098a3e2b2 100644
--- a/src/uu/basename/src/basename.rs
+++ b/src/uu/basename/src/basename.rs
@@ -110,7 +110,7 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
 
     let line_ending = if opt_zero { "\0" } else { "\n" };
     for path in paths {
-        print!("{}{}", basename(&path, &suffix), line_ending);
+        print!("{}{}", basename(path, suffix), line_ending);
     }
 
     0
@@ -118,14 +118,7 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
 
 fn basename(fullname: &str, suffix: &str) -> String {
     // Remove all platform-specific path separators from the end
-    let mut path: String = fullname
-        .chars()
-        .rev()
-        .skip_while(|&ch| is_separator(ch))
-        .collect();
-
-    // Undo reverse
-    path = path.chars().rev().collect();
+    let path = fullname.trim_end_matches(is_separator);
 
     // Convert to path buffer and get last path component
     let pb = PathBuf::from(path);
diff --git a/src/uu/cat/Cargo.toml b/src/uu/cat/Cargo.toml
index 09b289253..9218e84fe 100644
--- a/src/uu/cat/Cargo.toml
+++ b/src/uu/cat/Cargo.toml
@@ -17,6 +17,7 @@ path = "src/cat.rs"
 [dependencies]
 clap = "2.33"
 thiserror = "1.0"
+atty = "0.2"
 uucore = { version=">=0.0.8", package="uucore", path="../../uucore", features=["fs"] }
 uucore_procs = { version=">=0.0.5", package="uucore_procs", path="../../uucore_procs" }
 
diff --git a/src/uu/cat/src/cat.rs b/src/uu/cat/src/cat.rs
index 1f2f441d8..889ba424a 100644
--- a/src/uu/cat/src/cat.rs
+++ b/src/uu/cat/src/cat.rs
@@ -20,7 +20,6 @@ use clap::{crate_version, App, Arg};
 use std::fs::{metadata, File};
 use std::io::{self, Read, Write};
 use thiserror::Error;
-use uucore::fs::is_stdin_interactive;
 
 /// Linux splice support
 #[cfg(any(target_os = "linux", target_os = "android"))]
@@ -295,7 +294,7 @@ fn cat_handle<R: Read>(
     if options.can_write_fast() {
         write_fast(handle)
     } else {
-        write_lines(handle, &options, state)
+        write_lines(handle, options, state)
     }
 }
 
@@ -306,9 +305,9 @@ fn cat_path(path: &str, options: &OutputOptions, state: &mut OutputState) -> Cat
             #[cfg(any(target_os = "linux", target_os = "android"))]
             file_descriptor: stdin.as_raw_fd(),
             reader: stdin,
-            is_interactive: is_stdin_interactive(),
+            is_interactive: atty::is(atty::Stream::Stdin),
         };
-        return cat_handle(&mut handle, &options, state);
+        return cat_handle(&mut handle, options, state);
     }
     match get_input_type(path)? {
         InputType::Directory => Err(CatError::IsDirectory),
@@ -322,7 +321,7 @@ fn cat_path(path: &str, options: &OutputOptions, state: &mut OutputState) -> Cat
                 reader: socket,
                 is_interactive: false,
             };
-            cat_handle(&mut handle, &options, state)
+            cat_handle(&mut handle, options, state)
         }
         _ => {
             let file = File::open(path)?;
@@ -332,7 +331,7 @@ fn cat_path(path: &str, options: &OutputOptions, state: &mut OutputState) -> Cat
                 reader: file,
                 is_interactive: false,
             };
-            cat_handle(&mut handle, &options, state)
+            cat_handle(&mut handle, options, state)
         }
     }
 }
@@ -345,7 +344,7 @@ fn cat_files(files: Vec<String>, options: &OutputOptions) -> Result<(), u32> {
     };
 
     for path in &files {
-        if let Err(err) = cat_path(path, &options, &mut state) {
+        if let Err(err) = cat_path(path, options, &mut state) {
             show_error!("{}: {}", path, err);
             error_count += 1;
         }
diff --git a/src/uu/chgrp/Cargo.toml b/src/uu/chgrp/Cargo.toml
index 9424ad35e..0e43f7c02 100644
--- a/src/uu/chgrp/Cargo.toml
+++ b/src/uu/chgrp/Cargo.toml
@@ -15,6 +15,7 @@ edition = "2018"
 path = "src/chgrp.rs"
 
 [dependencies]
+clap = "2.33"
 uucore = { version=">=0.0.8", package="uucore", path="../../uucore", features=["entries", "fs", "perms"] }
 uucore_procs = { version=">=0.0.5", package="uucore_procs", path="../../uucore_procs" }
 walkdir = "2.2"
diff --git a/src/uu/chgrp/src/chgrp.rs b/src/uu/chgrp/src/chgrp.rs
index f6afc2805..454a0386c 100644
--- a/src/uu/chgrp/src/chgrp.rs
+++ b/src/uu/chgrp/src/chgrp.rs
@@ -14,6 +14,8 @@ use uucore::fs::resolve_relative_path;
 use uucore::libc::gid_t;
 use uucore::perms::{wrap_chgrp, Verbosity};
 
+use clap::{App, Arg};
+
 extern crate walkdir;
 use walkdir::WalkDir;
 
@@ -24,76 +26,194 @@ use std::os::unix::fs::MetadataExt;
 use std::path::Path;
 use uucore::InvalidEncodingHandling;
 
-static SYNTAX: &str =
-    "chgrp [OPTION]... GROUP FILE...\n or :  chgrp [OPTION]... --reference=RFILE FILE...";
-static SUMMARY: &str = "Change the group of each FILE to GROUP.";
+static ABOUT: &str = "Change the group of each FILE to GROUP.";
+static VERSION: &str = env!("CARGO_PKG_VERSION");
+
+pub mod options {
+    pub mod verbosity {
+        pub static CHANGES: &str = "changes";
+        pub static QUIET: &str = "quiet";
+        pub static SILENT: &str = "silent";
+        pub static VERBOSE: &str = "verbose";
+    }
+    pub mod preserve_root {
+        pub static PRESERVE: &str = "preserve-root";
+        pub static NO_PRESERVE: &str = "no-preserve-root";
+    }
+    pub mod dereference {
+        pub static DEREFERENCE: &str = "dereference";
+        pub static NO_DEREFERENCE: &str = "no-dereference";
+    }
+    pub static RECURSIVE: &str = "recursive";
+    pub mod traverse {
+        pub static TRAVERSE: &str = "H";
+        pub static NO_TRAVERSE: &str = "P";
+        pub static EVERY: &str = "L";
+    }
+    pub static REFERENCE: &str = "reference";
+    pub static ARG_GROUP: &str = "GROUP";
+    pub static ARG_FILES: &str = "FILE";
+}
 
 const FTS_COMFOLLOW: u8 = 1;
 const FTS_PHYSICAL: u8 = 1 << 1;
 const FTS_LOGICAL: u8 = 1 << 2;
 
+fn get_usage() -> String {
+    format!(
+        "{0} [OPTION]... GROUP FILE...\n    {0} [OPTION]... --reference=RFILE FILE...",
+        executable!()
+    )
+}
+
 pub fn uumain(args: impl uucore::Args) -> i32 {
     let args = args
         .collect_str(InvalidEncodingHandling::ConvertLossy)
         .accept_any();
 
-    let mut opts = app!(SYNTAX, SUMMARY, "");
-    opts.optflag("c",
-                 "changes",
-                 "like verbose but report only when a change is made")
-        .optflag("f", "silent", "")
-        .optflag("", "quiet", "suppress most error messages")
-        .optflag("v",
-                 "verbose",
-                 "output a diagnostic for every file processed")
-        .optflag("", "dereference", "affect the referent of each symbolic link (this is the default), rather than the symbolic link itself")
-        .optflag("h", "no-dereference", "affect symbolic links instead of any referenced file (useful only on systems that can change the ownership of a symlink)")
-        .optflag("",
-                 "no-preserve-root",
-                 "do not treat '/' specially (the default)")
-        .optflag("", "preserve-root", "fail to operate recursively on '/'")
-        .optopt("",
-                "reference",
-                "use RFILE's owner and group rather than specifying OWNER:GROUP values",
-                "RFILE")
-        .optflag("R",
-                 "recursive",
-                 "operate on files and directories recursively")
-        .optflag("H",
-                 "",
-                 "if a command line argument is a symbolic link to a directory, traverse it")
-        .optflag("L",
-                 "",
-                 "traverse every symbolic link to a directory encountered")
-        .optflag("P", "", "do not traverse any symbolic links (default)");
+    let usage = get_usage();
 
-    let mut bit_flag = FTS_PHYSICAL;
-    let mut preserve_root = false;
-    let mut derefer = -1;
-    let flags: &[char] = &['H', 'L', 'P'];
-    for opt in &args {
-        match opt.as_str() {
-            // If more than one is specified, only the final one takes effect.
-            s if s.contains(flags) => {
-                if let Some(idx) = s.rfind(flags) {
-                    match s.chars().nth(idx).unwrap() {
-                        'H' => bit_flag = FTS_COMFOLLOW | FTS_PHYSICAL,
-                        'L' => bit_flag = FTS_LOGICAL,
-                        'P' => bit_flag = FTS_PHYSICAL,
-                        _ => (),
-                    }
-                }
-            }
-            "--no-preserve-root" => preserve_root = false,
-            "--preserve-root" => preserve_root = true,
-            "--dereference" => derefer = 1,
-            "--no-dereference" => derefer = 0,
-            _ => (),
+    let mut app = App::new(executable!())
+        .version(VERSION)
+        .about(ABOUT)
+        .usage(&usage[..])
+        .arg(
+            Arg::with_name(options::verbosity::CHANGES)
+                .short("c")
+                .long(options::verbosity::CHANGES)
+                .help("like verbose but report only when a change is made"),
+        )
+        .arg(
+            Arg::with_name(options::verbosity::SILENT)
+                .short("f")
+                .long(options::verbosity::SILENT),
+        )
+        .arg(
+            Arg::with_name(options::verbosity::QUIET)
+                .long(options::verbosity::QUIET)
+                .help("suppress most error messages"),
+        )
+        .arg(
+            Arg::with_name(options::verbosity::VERBOSE)
+                .short("v")
+                .long(options::verbosity::VERBOSE)
+                .help("output a diagnostic for every file processed"),
+        )
+        .arg(
+            Arg::with_name(options::dereference::DEREFERENCE)
+                .long(options::dereference::DEREFERENCE),
+        )
+        .arg(
+           Arg::with_name(options::dereference::NO_DEREFERENCE)
+               .short("h")
+               .long(options::dereference::NO_DEREFERENCE)
+               .help(
+                   "affect symbolic links instead of any referenced file (useful only on systems that can change the ownership of a symlink)",
+               ),
+        )
+        .arg(
+            Arg::with_name(options::preserve_root::PRESERVE)
+                .long(options::preserve_root::PRESERVE)
+                .help("fail to operate recursively on '/'"),
+        )
+        .arg(
+            Arg::with_name(options::preserve_root::NO_PRESERVE)
+                .long(options::preserve_root::NO_PRESERVE)
+                .help("do not treat '/' specially (the default)"),
+        )
+        .arg(
+            Arg::with_name(options::REFERENCE)
+                .long(options::REFERENCE)
+                .value_name("RFILE")
+                .help("use RFILE's group rather than specifying GROUP values")
+                .takes_value(true)
+                .multiple(false),
+        )
+        .arg(
+            Arg::with_name(options::RECURSIVE)
+                .short("R")
+                .long(options::RECURSIVE)
+                .help("operate on files and directories recursively"),
+        )
+        .arg(
+            Arg::with_name(options::traverse::TRAVERSE)
+                .short(options::traverse::TRAVERSE)
+                .help("if a command line argument is a symbolic link to a directory, traverse it"),
+        )
+        .arg(
+            Arg::with_name(options::traverse::NO_TRAVERSE)
+                .short(options::traverse::NO_TRAVERSE)
+                .help("do not traverse any symbolic links (default)")
+                .overrides_with_all(&[options::traverse::TRAVERSE, options::traverse::EVERY]),
+        )
+        .arg(
+            Arg::with_name(options::traverse::EVERY)
+                .short(options::traverse::EVERY)
+                .help("traverse every symbolic link to a directory encountered"),
+        );
+
+    // we change the positional args based on whether
+    // --reference was used.
+    let mut reference = false;
+    let mut help = false;
+    // stop processing options on --
+    for arg in args.iter().take_while(|s| *s != "--") {
+        if arg.starts_with("--reference=") || arg == "--reference" {
+            reference = true;
+        } else if arg == "--help" {
+            // we stop processing once we see --help,
+            // as it doesn't matter if we've seen reference or not
+            help = true;
+            break;
         }
     }
 
-    let matches = opts.parse(args);
-    let recursive = matches.opt_present("recursive");
+    if help || !reference {
+        // add both positional arguments
+        app = app.arg(
+            Arg::with_name(options::ARG_GROUP)
+                .value_name(options::ARG_GROUP)
+                .required(true)
+                .takes_value(true)
+                .multiple(false),
+        )
+    }
+    app = app.arg(
+        Arg::with_name(options::ARG_FILES)
+            .value_name(options::ARG_FILES)
+            .multiple(true)
+            .takes_value(true)
+            .required(true)
+            .min_values(1),
+    );
+
+    let matches = app.get_matches_from(args);
+
+    /* Get the list of files */
+    let files: Vec<String> = matches
+        .values_of(options::ARG_FILES)
+        .map(|v| v.map(ToString::to_string).collect())
+        .unwrap_or_default();
+
+    let preserve_root = matches.is_present(options::preserve_root::PRESERVE);
+
+    let mut derefer = if matches.is_present(options::dereference::DEREFERENCE) {
+        1
+    } else if matches.is_present(options::dereference::NO_DEREFERENCE) {
+        0
+    } else {
+        -1
+    };
+
+    let mut bit_flag = if matches.is_present(options::traverse::TRAVERSE) {
+        FTS_COMFOLLOW | FTS_PHYSICAL
+    } else if matches.is_present(options::traverse::EVERY) {
+        FTS_LOGICAL
+    } else {
+        FTS_PHYSICAL
+    };
+
+    let recursive = matches.is_present(options::RECURSIVE);
     if recursive {
         if bit_flag == FTS_PHYSICAL {
             if derefer == 1 {
@@ -106,27 +226,20 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
         bit_flag = FTS_PHYSICAL;
     }
 
-    let verbosity = if matches.opt_present("changes") {
+    let verbosity = if matches.is_present(options::verbosity::CHANGES) {
         Verbosity::Changes
-    } else if matches.opt_present("silent") || matches.opt_present("quiet") {
+    } else if matches.is_present(options::verbosity::SILENT)
+        || matches.is_present(options::verbosity::QUIET)
+    {
         Verbosity::Silent
-    } else if matches.opt_present("verbose") {
+    } else if matches.is_present(options::verbosity::VERBOSE) {
         Verbosity::Verbose
     } else {
         Verbosity::Normal
     };
 
-    if matches.free.is_empty() {
-        show_usage_error!("missing operand");
-        return 1;
-    } else if matches.free.len() < 2 && !matches.opt_present("reference") {
-        show_usage_error!("missing operand after ‘{}’", matches.free[0]);
-        return 1;
-    }
-
-    let dest_gid: gid_t;
-    let mut files;
-    if let Some(file) = matches.opt_str("reference") {
+    let dest_gid: u32;
+    if let Some(file) = matches.value_of(options::REFERENCE) {
         match fs::metadata(&file) {
             Ok(meta) => {
                 dest_gid = meta.gid();
@@ -136,19 +249,17 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
                 return 1;
             }
         }
-        files = matches.free;
     } else {
-        match entries::grp2gid(&matches.free[0]) {
+        let group = matches.value_of(options::ARG_GROUP).unwrap_or_default();
+        match entries::grp2gid(group) {
             Ok(g) => {
                 dest_gid = g;
             }
             _ => {
-                show_error!("invalid group: {}", matches.free[0].as_str());
+                show_error!("invalid group: {}", group);
                 return 1;
             }
         }
-        files = matches.free;
-        files.remove(0);
     }
 
     let executor = Chgrper {
diff --git a/src/uu/chmod/src/chmod.rs b/src/uu/chmod/src/chmod.rs
index 9cdabc7d6..2d5787099 100644
--- a/src/uu/chmod/src/chmod.rs
+++ b/src/uu/chmod/src/chmod.rs
@@ -127,31 +127,32 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
     let verbose = matches.is_present(options::VERBOSE);
     let preserve_root = matches.is_present(options::PRESERVE_ROOT);
     let recursive = matches.is_present(options::RECURSIVE);
-    let fmode =
-        matches
-            .value_of(options::REFERENCE)
-            .and_then(|ref fref| match fs::metadata(fref) {
-                Ok(meta) => Some(meta.mode()),
-                Err(err) => crash!(1, "cannot stat attributes of '{}': {}", fref, err),
-            });
+    let fmode = matches
+        .value_of(options::REFERENCE)
+        .and_then(|fref| match fs::metadata(fref) {
+            Ok(meta) => Some(meta.mode()),
+            Err(err) => crash!(1, "cannot stat attributes of '{}': {}", fref, err),
+        });
     let modes = matches.value_of(options::MODE).unwrap(); // should always be Some because required
-    let mut cmode = if mode_had_minus_prefix {
+    let cmode = if mode_had_minus_prefix {
         // clap parsing is finished, now put prefix back
-        Some(format!("-{}", modes))
+        format!("-{}", modes)
     } else {
-        Some(modes.to_string())
+        modes.to_string()
     };
     let mut files: Vec<String> = matches
         .values_of(options::FILE)
         .map(|v| v.map(ToString::to_string).collect())
         .unwrap_or_default();
-    if fmode.is_some() {
+    let cmode = if fmode.is_some() {
         // "--reference" and MODE are mutually exclusive
         // if "--reference" was used MODE needs to be interpreted as another FILE
         // it wasn't possible to implement this behavior directly with clap
-        files.push(cmode.unwrap());
-        cmode = None;
-    }
+        files.push(cmode);
+        None
+    } else {
+        Some(cmode)
+    };
 
     let chmoder = Chmoder {
         changes,
@@ -230,11 +231,11 @@ impl Chmoder {
                 return Err(1);
             }
             if !self.recursive {
-                r = self.chmod_file(&file).and(r);
+                r = self.chmod_file(file).and(r);
             } else {
                 for entry in WalkDir::new(&filename).into_iter().filter_map(|e| e.ok()) {
                     let file = entry.path();
-                    r = self.chmod_file(&file).and(r);
+                    r = self.chmod_file(file).and(r);
                 }
             }
         }
diff --git a/src/uu/chown/src/chown.rs b/src/uu/chown/src/chown.rs
index 2bb5133fe..ab9f10dba 100644
--- a/src/uu/chown/src/chown.rs
+++ b/src/uu/chown/src/chown.rs
@@ -220,7 +220,7 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
     };
 
     let filter = if let Some(spec) = matches.value_of(options::FROM) {
-        match parse_spec(&spec) {
+        match parse_spec(spec) {
             Ok((Some(uid), None)) => IfFrom::User(uid),
             Ok((None, Some(gid))) => IfFrom::Group(gid),
             Ok((Some(uid), Some(gid))) => IfFrom::UserGroup(uid, gid),
@@ -248,7 +248,7 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
             }
         }
     } else {
-        match parse_spec(&owner) {
+        match parse_spec(owner) {
             Ok((u, g)) => {
                 dest_uid = u;
                 dest_gid = g;
@@ -278,37 +278,25 @@ fn parse_spec(spec: &str) -> Result<(Option<u32>, Option<u32>), String> {
     let usr_only = args.len() == 1 && !args[0].is_empty();
     let grp_only = args.len() == 2 && args[0].is_empty();
     let usr_grp = args.len() == 2 && !args[0].is_empty() && !args[1].is_empty();
-
-    if usr_only {
-        Ok((
-            Some(match Passwd::locate(args[0]) {
-                Ok(v) => v.uid(),
-                _ => return Err(format!("invalid user: ‘{}’", spec)),
-            }),
-            None,
-        ))
-    } else if grp_only {
-        Ok((
-            None,
-            Some(match Group::locate(args[1]) {
-                Ok(v) => v.gid(),
-                _ => return Err(format!("invalid group: ‘{}’", spec)),
-            }),
-        ))
-    } else if usr_grp {
-        Ok((
-            Some(match Passwd::locate(args[0]) {
-                Ok(v) => v.uid(),
-                _ => return Err(format!("invalid user: ‘{}’", spec)),
-            }),
-            Some(match Group::locate(args[1]) {
-                Ok(v) => v.gid(),
-                _ => return Err(format!("invalid group: ‘{}’", spec)),
-            }),
-        ))
+    let uid = if usr_only || usr_grp {
+        Some(
+            Passwd::locate(args[0])
+                .map_err(|_| format!("invalid user: ‘{}’", spec))?
+                .uid(),
+        )
     } else {
-        Ok((None, None))
-    }
+        None
+    };
+    let gid = if grp_only || usr_grp {
+        Some(
+            Group::locate(args[1])
+                .map_err(|_| format!("invalid group: ‘{}’", spec))?
+                .gid(),
+        )
+    } else {
+        None
+    };
+    Ok((uid, gid))
 }
 
 enum IfFrom {
@@ -497,3 +485,17 @@ impl Chowner {
         }
     }
 }
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn test_parse_spec() {
+        assert_eq!(parse_spec(":"), Ok((None, None)));
+        assert!(parse_spec("::")
+            .err()
+            .unwrap()
+            .starts_with("invalid group: "));
+    }
+}
diff --git a/src/uu/chroot/src/chroot.rs b/src/uu/chroot/src/chroot.rs
index a05bd4494..86d4a4900 100644
--- a/src/uu/chroot/src/chroot.rs
+++ b/src/uu/chroot/src/chroot.rs
@@ -28,6 +28,7 @@ mod options {
     pub const GROUP: &str = "group";
     pub const GROUPS: &str = "groups";
     pub const USERSPEC: &str = "userspec";
+    pub const COMMAND: &str = "command";
 }
 
 pub fn uumain(args: impl uucore::Args) -> i32 {
@@ -39,7 +40,12 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
         .version(crate_version!())
         .about(ABOUT)
         .usage(SYNTAX)
-        .arg(Arg::with_name(options::NEWROOT).hidden(true).required(true))
+        .arg(
+            Arg::with_name(options::NEWROOT)
+                .hidden(true)
+                .required(true)
+                .index(1),
+        )
         .arg(
             Arg::with_name(options::USER)
                 .short("u")
@@ -71,6 +77,12 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
                 )
                 .value_name("USER:GROUP"),
         )
+        .arg(
+            Arg::with_name(options::COMMAND)
+                .hidden(true)
+                .multiple(true)
+                .index(2),
+        )
         .get_matches_from(args);
 
     let default_shell: &'static str = "/bin/sh";
@@ -94,7 +106,14 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
         );
     }
 
-    let command: Vec<&str> = match matches.args.len() {
+    let commands = match matches.values_of(options::COMMAND) {
+        Some(v) => v.collect(),
+        None => vec![],
+    };
+
+    // TODO: refactor the args and command matching
+    // See: https://github.com/uutils/coreutils/pull/2365#discussion_r647849967
+    let command: Vec<&str> = match commands.len() {
         1 => {
             let shell: &str = match user_shell {
                 Err(_) => default_shell,
@@ -102,17 +121,10 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
             };
             vec![shell, default_option]
         }
-        _ => {
-            let mut vector: Vec<&str> = Vec::new();
-            for (&k, v) in matches.args.iter() {
-                vector.push(k);
-                vector.push(&v.vals[0].to_str().unwrap());
-            }
-            vector
-        }
+        _ => commands,
     };
 
-    set_context(&newroot, &matches);
+    set_context(newroot, &matches);
 
     let pstatus = Command::new(command[0])
         .args(&command[1..])
@@ -132,7 +144,7 @@ fn set_context(root: &Path, options: &clap::ArgMatches) {
     let group_str = options.value_of(options::GROUP).unwrap_or_default();
     let groups_str = options.value_of(options::GROUPS).unwrap_or_default();
     let userspec = match userspec_str {
-        Some(ref u) => {
+        Some(u) => {
             let s: Vec<&str> = u.split(':').collect();
             if s.len() != 2 || s.iter().any(|&spec| spec.is_empty()) {
                 crash!(1, "invalid userspec: `{}`", u)
diff --git a/src/uu/cksum/src/cksum.rs b/src/uu/cksum/src/cksum.rs
index 49c0536f5..6a812c186 100644
--- a/src/uu/cksum/src/cksum.rs
+++ b/src/uu/cksum/src/cksum.rs
@@ -160,18 +160,14 @@ fn cksum(fname: &str) -> io::Result<(u32, usize)> {
 
     let mut bytes = init_byte_array();
     loop {
-        match rd.read(&mut bytes) {
-            Ok(num_bytes) => {
-                if num_bytes == 0 {
-                    return Ok((crc_final(crc, size), size));
-                }
-                for &b in bytes[..num_bytes].iter() {
-                    crc = crc_update(crc, b);
-                }
-                size += num_bytes;
-            }
-            Err(err) => return Err(err),
+        let num_bytes = rd.read(&mut bytes)?;
+        if num_bytes == 0 {
+            return Ok((crc_final(crc, size), size));
         }
+        for &b in bytes[..num_bytes].iter() {
+            crc = crc_update(crc, b);
+        }
+        size += num_bytes;
     }
 }
 
diff --git a/src/uu/comm/src/comm.rs b/src/uu/comm/src/comm.rs
index f7190fb73..7a6086bb5 100644
--- a/src/uu/comm/src/comm.rs
+++ b/src/uu/comm/src/comm.rs
@@ -50,9 +50,8 @@ fn mkdelim(col: usize, opts: &ArgMatches) -> String {
 }
 
 fn ensure_nl(line: &mut String) {
-    match line.chars().last() {
-        Some('\n') => (),
-        _ => line.push('\n'),
+    if !line.ends_with('\n') {
+        line.push('\n');
     }
 }
 
diff --git a/src/uu/cp/src/cp.rs b/src/uu/cp/src/cp.rs
index 6a114cf44..a87e86b98 100644
--- a/src/uu/cp/src/cp.rs
+++ b/src/uu/cp/src/cp.rs
@@ -709,27 +709,26 @@ fn parse_path_args(path_args: &[String], options: &Options) -> CopyResult<(Vec<S
         return Err(format!("extra operand {:?}", paths[2]).into());
     }
 
-    let (mut sources, target) = match options.target_dir {
+    let target = match options.target_dir {
         Some(ref target) => {
             // All path args are sources, and the target dir was
             // specified separately
-            (paths, PathBuf::from(target))
+            PathBuf::from(target)
         }
         None => {
             // If there was no explicit target-dir, then use the last
             // path_arg
-            let target = paths.pop().unwrap();
-            (paths, target)
+            paths.pop().unwrap()
         }
     };
 
     if options.strip_trailing_slashes {
-        for source in sources.iter_mut() {
+        for source in paths.iter_mut() {
             *source = source.components().as_path().to_owned()
         }
     }
 
-    Ok((sources, target))
+    Ok((paths, target))
 }
 
 fn preserve_hardlinks(
@@ -1088,7 +1087,7 @@ fn copy_attribute(source: &Path, dest: &Path, attribute: &Attribute) -> CopyResu
 }
 
 #[cfg(not(windows))]
-#[allow(clippy::unnecessary_unwrap)] // needed for windows version
+#[allow(clippy::unnecessary_wraps)] // needed for windows version
 fn symlink_file(source: &Path, dest: &Path, context: &str) -> CopyResult<()> {
     match std::os::unix::fs::symlink(source, dest).context(context) {
         Ok(_) => Ok(()),
@@ -1271,15 +1270,15 @@ fn copy_on_write_linux(source: &Path, dest: &Path, mode: ReflinkMode) -> CopyRes
         ReflinkMode::Always => unsafe {
             let result = ficlone(dst_file.as_raw_fd(), src_file.as_raw_fd() as *const i32);
             if result != 0 {
-                return Err(format!(
+                Err(format!(
                     "failed to clone {:?} from {:?}: {}",
                     source,
                     dest,
                     std::io::Error::last_os_error()
                 )
-                .into());
+                .into())
             } else {
-                return Ok(());
+                Ok(())
             }
         },
         ReflinkMode::Auto => unsafe {
@@ -1287,11 +1286,10 @@ fn copy_on_write_linux(source: &Path, dest: &Path, mode: ReflinkMode) -> CopyRes
             if result != 0 {
                 fs::copy(source, dest).context(&*context_for(source, dest))?;
             }
+            Ok(())
         },
         ReflinkMode::Never => unreachable!(),
     }
-
-    Ok(())
 }
 
 /// Copies `source` to `dest` using copy-on-write if possible.
diff --git a/src/uu/csplit/src/csplit.rs b/src/uu/csplit/src/csplit.rs
index e3b2069ab..d69254a3a 100644
--- a/src/uu/csplit/src/csplit.rs
+++ b/src/uu/csplit/src/csplit.rs
@@ -92,7 +92,7 @@ where
     T: BufRead,
 {
     let mut input_iter = InputSplitter::new(input.lines().enumerate());
-    let mut split_writer = SplitWriter::new(&options);
+    let mut split_writer = SplitWriter::new(options);
     let ret = do_csplit(&mut split_writer, patterns, &mut input_iter);
 
     // consume the rest
diff --git a/src/uu/csplit/src/patterns.rs b/src/uu/csplit/src/patterns.rs
index 5621d18a3..4ab7862ac 100644
--- a/src/uu/csplit/src/patterns.rs
+++ b/src/uu/csplit/src/patterns.rs
@@ -133,20 +133,12 @@ fn extract_patterns(args: &[String]) -> Result<Vec<Pattern>, CsplitError> {
                 Some(m) => m.as_str().parse().unwrap(),
             };
             if let Some(up_to_match) = captures.name("UPTO") {
-                let pattern = match Regex::new(up_to_match.as_str()) {
-                    Err(_) => {
-                        return Err(CsplitError::InvalidPattern(arg.to_string()));
-                    }
-                    Ok(reg) => reg,
-                };
+                let pattern = Regex::new(up_to_match.as_str())
+                    .map_err(|_| CsplitError::InvalidPattern(arg.to_string()))?;
                 patterns.push(Pattern::UpToMatch(pattern, offset, execute_ntimes));
             } else if let Some(skip_to_match) = captures.name("SKIPTO") {
-                let pattern = match Regex::new(skip_to_match.as_str()) {
-                    Err(_) => {
-                        return Err(CsplitError::InvalidPattern(arg.to_string()));
-                    }
-                    Ok(reg) => reg,
-                };
+                let pattern = Regex::new(skip_to_match.as_str())
+                    .map_err(|_| CsplitError::InvalidPattern(arg.to_string()))?;
                 patterns.push(Pattern::SkipToMatch(pattern, offset, execute_ntimes));
             }
         } else if let Ok(line_number) = arg.parse::<usize>() {
diff --git a/src/uu/csplit/src/split_name.rs b/src/uu/csplit/src/split_name.rs
index 6db781e9b..758216414 100644
--- a/src/uu/csplit/src/split_name.rs
+++ b/src/uu/csplit/src/split_name.rs
@@ -33,13 +33,13 @@ impl SplitName {
         // get the prefix
         let prefix = prefix_opt.unwrap_or_else(|| "xx".to_string());
         // the width for the split offset
-        let n_digits = match n_digits_opt {
-            None => 2,
-            Some(opt) => match opt.parse::<usize>() {
-                Ok(digits) => digits,
-                Err(_) => return Err(CsplitError::InvalidNumber(opt)),
-            },
-        };
+        let n_digits = n_digits_opt
+            .map(|opt| {
+                opt.parse::<usize>()
+                    .map_err(|_| CsplitError::InvalidNumber(opt))
+            })
+            .transpose()?
+            .unwrap_or(2);
         // translate the custom format into a function
         let fn_split_name: Box<dyn Fn(usize) -> String> = match format_opt {
             None => Box::new(move |n: usize| -> String {
diff --git a/src/uu/cut/Cargo.toml b/src/uu/cut/Cargo.toml
index c863c1772..47b8223c5 100644
--- a/src/uu/cut/Cargo.toml
+++ b/src/uu/cut/Cargo.toml
@@ -20,6 +20,7 @@ uucore = { version=">=0.0.8", package="uucore", path="../../uucore" }
 uucore_procs = { version=">=0.0.5", package="uucore_procs", path="../../uucore_procs" }
 memchr = "2"
 bstr = "0.2"
+atty = "0.2"
 
 [[bin]]
 name = "cut"
diff --git a/src/uu/cut/src/cut.rs b/src/uu/cut/src/cut.rs
index 819cbb989..af4a27d8a 100644
--- a/src/uu/cut/src/cut.rs
+++ b/src/uu/cut/src/cut.rs
@@ -17,7 +17,6 @@ use std::io::{stdin, stdout, BufReader, BufWriter, Read, Write};
 use std::path::Path;
 
 use self::searcher::Searcher;
-use uucore::fs::is_stdout_interactive;
 use uucore::ranges::Range;
 use uucore::InvalidEncodingHandling;
 
@@ -127,7 +126,7 @@ enum Mode {
 }
 
 fn stdout_writer() -> Box<dyn Write> {
-    if is_stdout_interactive() {
+    if atty::is(atty::Stream::Stdout) {
         Box::new(stdout())
     } else {
         Box::new(BufWriter::new(stdout())) as Box<dyn Write>
diff --git a/src/uu/du/Cargo.toml b/src/uu/du/Cargo.toml
index 023c0a021..dcd1f720e 100644
--- a/src/uu/du/Cargo.toml
+++ b/src/uu/du/Cargo.toml
@@ -19,6 +19,8 @@ clap = "2.33"
 chrono = "0.4"
 uucore = { version=">=0.0.8", package="uucore", path="../../uucore" }
 uucore_procs = { version=">=0.0.5", package="uucore_procs", path="../../uucore_procs" }
+
+[target.'cfg(target_os = "windows")'.dependencies]
 winapi = { version="0.3", features=[] }
 
 [[bin]]
diff --git a/src/uu/du/src/du.rs b/src/uu/du/src/du.rs
index c5fff2ed7..b7c53eb72 100644
--- a/src/uu/du/src/du.rs
+++ b/src/uu/du/src/du.rs
@@ -1,9 +1,9 @@
-// This file is part of the uutils coreutils package.
-//
-// (c) Derek Chiang <derekchiang93@gmail.com>
-//
-// For the full copyright and license information, please view the LICENSE
-// file that was distributed with this source code.
+//  * This file is part of the uutils coreutils package.
+//  *
+//  * (c) Derek Chiang <derekchiang93@gmail.com>
+//  *
+//  * For the full copyright and license information, please view the LICENSE
+//  * file that was distributed with this source code.
 
 #[macro_use]
 extern crate uucore;
@@ -12,6 +12,7 @@ use chrono::prelude::DateTime;
 use chrono::Local;
 use clap::{crate_version, App, Arg};
 use std::collections::HashSet;
+use std::convert::TryFrom;
 use std::env;
 use std::fs;
 #[cfg(not(windows))]
@@ -24,8 +25,11 @@ use std::os::unix::fs::MetadataExt;
 use std::os::windows::fs::MetadataExt;
 #[cfg(windows)]
 use std::os::windows::io::AsRawHandle;
+#[cfg(windows)]
+use std::path::Path;
 use std::path::PathBuf;
 use std::time::{Duration, UNIX_EPOCH};
+use uucore::parse_size::{parse_size, ParseSizeError};
 use uucore::InvalidEncodingHandling;
 #[cfg(windows)]
 use winapi::shared::minwindef::{DWORD, LPVOID};
@@ -42,7 +46,7 @@ mod options {
     pub const NULL: &str = "0";
     pub const ALL: &str = "all";
     pub const APPARENT_SIZE: &str = "apparent-size";
-    pub const BLOCK_SIZE: &str = "B";
+    pub const BLOCK_SIZE: &str = "block-size";
     pub const BYTES: &str = "b";
     pub const TOTAL: &str = "c";
     pub const MAX_DEPTH: &str = "d";
@@ -55,6 +59,7 @@ mod options {
     pub const SI: &str = "si";
     pub const TIME: &str = "time";
     pub const TIME_STYLE: &str = "time-style";
+    pub const ONE_FILE_SYSTEM: &str = "one-file-system";
     pub const FILE: &str = "FILE";
 }
 
@@ -79,6 +84,7 @@ struct Options {
     max_depth: Option<usize>,
     total: bool,
     separate_dirs: bool,
+    one_file_system: bool,
 }
 
 #[derive(PartialEq, Eq, Hash, Clone, Copy)]
@@ -159,7 +165,7 @@ fn birth_u64(meta: &Metadata) -> Option<u64> {
 }
 
 #[cfg(windows)]
-fn get_size_on_disk(path: &PathBuf) -> u64 {
+fn get_size_on_disk(path: &Path) -> u64 {
     let mut size_on_disk = 0;
 
     // bind file so it stays in scope until end of function
@@ -191,7 +197,7 @@ fn get_size_on_disk(path: &PathBuf) -> u64 {
 }
 
 #[cfg(windows)]
-fn get_file_info(path: &PathBuf) -> Option<FileInfo> {
+fn get_file_info(path: &Path) -> Option<FileInfo> {
     let mut result = None;
 
     let file = match fs::File::open(path) {
@@ -223,64 +229,22 @@ fn get_file_info(path: &PathBuf) -> Option<FileInfo> {
     result
 }
 
-fn unit_string_to_number(s: &str) -> Option<u64> {
-    let mut offset = 0;
-    let mut s_chars = s.chars().rev();
-
-    let (mut ch, multiple) = match s_chars.next() {
-        Some('B') | Some('b') => ('B', 1000u64),
-        Some(ch) => (ch, 1024u64),
-        None => return None,
-    };
-    if ch == 'B' {
-        ch = s_chars.next()?;
-        offset += 1;
-    }
-    ch = ch.to_ascii_uppercase();
-
-    let unit = UNITS
-        .iter()
-        .rev()
-        .find(|&&(unit_ch, _)| unit_ch == ch)
-        .map(|&(_, val)| {
-            // we found a match, so increment offset
-            offset += 1;
-            val
-        })
-        .or_else(|| if multiple == 1024 { Some(0) } else { None })?;
-
-    let number = s[..s.len() - offset].parse::<u64>().ok()?;
-
-    Some(number * multiple.pow(unit))
-}
-
-fn translate_to_pure_number(s: &Option<&str>) -> Option<u64> {
-    match *s {
-        Some(ref s) => unit_string_to_number(s),
-        None => None,
-    }
-}
-
-fn read_block_size(s: Option<&str>) -> u64 {
-    match translate_to_pure_number(&s) {
-        Some(v) => v,
-        None => {
-            if let Some(value) = s {
-                show_error!("invalid --block-size argument '{}'", value);
-            };
-
-            for env_var in &["DU_BLOCK_SIZE", "BLOCK_SIZE", "BLOCKSIZE"] {
-                let env_size = env::var(env_var).ok();
-                if let Some(quantity) = translate_to_pure_number(&env_size.as_deref()) {
-                    return quantity;
+fn read_block_size(s: Option<&str>) -> usize {
+    if let Some(s) = s {
+        parse_size(s)
+            .unwrap_or_else(|e| crash!(1, "{}", format_error_message(e, s, options::BLOCK_SIZE)))
+    } else {
+        for env_var in &["DU_BLOCK_SIZE", "BLOCK_SIZE", "BLOCKSIZE"] {
+            if let Ok(env_size) = env::var(env_var) {
+                if let Ok(v) = parse_size(&env_size) {
+                    return v;
                 }
             }
-
-            if env::var("POSIXLY_CORRECT").is_ok() {
-                512
-            } else {
-                1024
-            }
+        }
+        if env::var("POSIXLY_CORRECT").is_ok() {
+            512
+        } else {
+            1024
         }
     }
 }
@@ -316,10 +280,18 @@ fn du(
                 Ok(entry) => match Stat::new(entry.path()) {
                     Ok(this_stat) => {
                         if this_stat.is_dir {
+                            if options.one_file_system {
+                                if let (Some(this_inode), Some(my_inode)) =
+                                    (this_stat.inode, my_stat.inode)
+                                {
+                                    if this_inode.dev_id != my_inode.dev_id {
+                                        continue;
+                                    }
+                                }
+                            }
                             futures.push(du(this_stat, options, depth + 1, inodes));
                         } else {
-                            if this_stat.inode.is_some() {
-                                let inode = this_stat.inode.unwrap();
+                            if let Some(inode) = this_stat.inode {
                                 if inodes.contains(&inode) {
                                     continue;
                                 }
@@ -358,7 +330,9 @@ fn du(
             my_stat.size += stat.size;
             my_stat.blocks += stat.blocks;
         }
-        options.max_depth == None || depth < options.max_depth.unwrap()
+        options
+            .max_depth
+            .map_or(true, |max_depth| depth < max_depth)
     }));
     stats.push(my_stat);
     Box::new(stats.into_iter())
@@ -431,12 +405,12 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
                     although  the apparent  size is usually smaller, it may be larger due to holes \
                     in ('sparse') files, internal  fragmentation,  indirect  blocks, and the like"
                 )
-                .alias("app") // The GNU testsuite uses this alias
+                .alias("app") // The GNU test suite uses this alias
         )
         .arg(
             Arg::with_name(options::BLOCK_SIZE)
                 .short("B")
-                .long("block-size")
+                .long(options::BLOCK_SIZE)
                 .value_name("SIZE")
                 .help(
                     "scale sizes  by  SIZE before printing them. \
@@ -530,12 +504,12 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
                 .long(options::SI)
                 .help("like -h, but use powers of 1000 not 1024")
         )
-        // .arg(
-        //     Arg::with_name("one-file-system")
-        //         .short("x")
-        //         .long("one-file-system")
-        //         .help("skip directories on different file systems")
-        // )
+        .arg(
+            Arg::with_name(options::ONE_FILE_SYSTEM)
+                .short("x")
+                .long(options::ONE_FILE_SYSTEM)
+                .help("skip directories on different file systems")
+        )
         // .arg(
         //     Arg::with_name("")
         //         .short("x")
@@ -583,12 +557,12 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
     let max_depth_str = matches.value_of(options::MAX_DEPTH);
     let max_depth = max_depth_str.as_ref().and_then(|s| s.parse::<usize>().ok());
     match (max_depth_str, max_depth) {
-        (Some(ref s), _) if summarize => {
-            show_error!("summarizing conflicts with --max-depth={}", *s);
+        (Some(s), _) if summarize => {
+            show_error!("summarizing conflicts with --max-depth={}", s);
             return 1;
         }
-        (Some(ref s), None) => {
-            show_error!("invalid maximum depth '{}'", *s);
+        (Some(s), None) => {
+            show_error!("invalid maximum depth '{}'", s);
             return 1;
         }
         (Some(_), Some(_)) | (None, _) => { /* valid */ }
@@ -600,6 +574,7 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
         max_depth,
         total: matches.is_present(options::TOTAL),
         separate_dirs: matches.is_present(options::SEPARATE_DIRS),
+        one_file_system: matches.is_present(options::ONE_FILE_SYSTEM),
     };
 
     let files = match matches.value_of(options::FILE) {
@@ -609,7 +584,7 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
         }
     };
 
-    let block_size = read_block_size(matches.value_of(options::BLOCK_SIZE));
+    let block_size = u64::try_from(read_block_size(matches.value_of(options::BLOCK_SIZE))).unwrap();
 
     let multiplier: u64 = if matches.is_present(options::SI) {
         1000
@@ -745,31 +720,27 @@ Try '{} --help' for more information.",
     0
 }
 
+fn format_error_message(error: ParseSizeError, s: &str, option: &str) -> String {
+    // NOTE:
+    // GNU's du echos affected flag, -B or --block-size (-t or --threshold), depending user's selection
+    // GNU's du does distinguish between "invalid (suffix in) argument"
+    match error {
+        ParseSizeError::ParseFailure(_) => format!("invalid --{} argument '{}'", option, s),
+        ParseSizeError::SizeTooBig(_) => format!("--{} argument '{}' too large", option, s),
+    }
+}
+
 #[cfg(test)]
 mod test_du {
     #[allow(unused_imports)]
     use super::*;
 
-    #[test]
-    fn test_translate_to_pure_number() {
-        let test_data = [
-            (Some("10".to_string()), Some(10)),
-            (Some("10K".to_string()), Some(10 * 1024)),
-            (Some("5M".to_string()), Some(5 * 1024 * 1024)),
-            (Some("900KB".to_string()), Some(900 * 1000)),
-            (Some("BAD_STRING".to_string()), None),
-        ];
-        for it in test_data.iter() {
-            assert_eq!(translate_to_pure_number(&it.0.as_deref()), it.1);
-        }
-    }
-
     #[test]
     fn test_read_block_size() {
         let test_data = [
-            (Some("10".to_string()), 10),
+            (Some("1024".to_string()), 1024),
+            (Some("K".to_string()), 1024),
             (None, 1024),
-            (Some("BAD_STRING".to_string()), 1024),
         ];
         for it in test_data.iter() {
             assert_eq!(read_block_size(it.0.as_deref()), it.1);
diff --git a/src/uu/echo/src/echo.rs b/src/uu/echo/src/echo.rs
index 56cd967f4..d83a4fe06 100644
--- a/src/uu/echo/src/echo.rs
+++ b/src/uu/echo/src/echo.rs
@@ -181,7 +181,7 @@ fn execute(no_newline: bool, escaped: bool, free: Vec<String>) -> io::Result<()>
             write!(output, " ")?;
         }
         if escaped {
-            let should_stop = print_escaped(&input, &mut output)?;
+            let should_stop = print_escaped(input, &mut output)?;
             if should_stop {
                 break;
             }
diff --git a/src/uu/env/src/env.rs b/src/uu/env/src/env.rs
index 50a327260..0ea66d7e9 100644
--- a/src/uu/env/src/env.rs
+++ b/src/uu/env/src/env.rs
@@ -82,13 +82,10 @@ fn load_config_file(opts: &mut Options) -> Result<(), i32> {
             Ini::load_from_file(file)
         };
 
-        let conf = match conf {
-            Ok(config) => config,
-            Err(error) => {
-                eprintln!("env: error: \"{}\": {}", file, error);
-                return Err(1);
-            }
-        };
+        let conf = conf.map_err(|error| {
+            eprintln!("env: error: \"{}\": {}", file, error);
+            1
+        })?;
 
         for (_, prop) in &conf {
             // ignore all INI section lines (treat them as comments)
@@ -245,7 +242,7 @@ fn run_env(args: impl uucore::Args) -> Result<(), i32> {
     }
 
     // set specified env vars
-    for &(ref name, ref val) in &opts.sets {
+    for &(name, val) in &opts.sets {
         // FIXME: set_var() panics if name is an empty string
         env::set_var(name, val);
     }
@@ -256,13 +253,10 @@ fn run_env(args: impl uucore::Args) -> Result<(), i32> {
 
         // FIXME: this should just use execvp() (no fork()) on Unix-like systems
         match Command::new(&*prog).args(args).status() {
-            Ok(exit) => {
-                if !exit.success() {
-                    return Err(exit.code().unwrap());
-                }
-            }
+            Ok(exit) if !exit.success() => return Err(exit.code().unwrap()),
             Err(ref err) if err.kind() == io::ErrorKind::NotFound => return Err(127),
             Err(_) => return Err(126),
+            Ok(_) => (),
         }
     } else {
         // no program provided, so just dump all env vars to stdout
diff --git a/src/uu/expand/src/expand.rs b/src/uu/expand/src/expand.rs
index 08a514dbf..d9d669e7c 100644
--- a/src/uu/expand/src/expand.rs
+++ b/src/uu/expand/src/expand.rs
@@ -15,7 +15,6 @@ extern crate uucore;
 use clap::{crate_version, App, Arg, ArgMatches};
 use std::fs::File;
 use std::io::{stdin, stdout, BufRead, BufReader, BufWriter, Read, Write};
-use std::iter::repeat;
 use std::str::from_utf8;
 use unicode_width::UnicodeWidthChar;
 
@@ -90,7 +89,7 @@ impl Options {
             })
             .max()
             .unwrap(); // length of tabstops is guaranteed >= 1
-        let tspaces = repeat(' ').take(nspaces).collect();
+        let tspaces = " ".repeat(nspaces);
 
         let files: Vec<String> = match matches.values_of(options::FILES) {
             Some(s) => s.map(|v| v.to_string()).collect(),
@@ -236,7 +235,7 @@ fn expand(options: Options) {
 
                         // now dump out either spaces if we're expanding, or a literal tab if we're not
                         if init || !options.iflag {
-                            safe_unwrap!(output.write_all(&options.tspaces[..nts].as_bytes()));
+                            safe_unwrap!(output.write_all(options.tspaces[..nts].as_bytes()));
                         } else {
                             safe_unwrap!(output.write_all(&buf[byte..byte + nbytes]));
                         }
diff --git a/src/uu/expr/src/expr.rs b/src/uu/expr/src/expr.rs
index 5d63bed80..8238917f7 100644
--- a/src/uu/expr/src/expr.rs
+++ b/src/uu/expr/src/expr.rs
@@ -37,7 +37,7 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
 }
 
 fn process_expr(token_strings: &[String]) -> Result<String, String> {
-    let maybe_tokens = tokens::strings_to_tokens(&token_strings);
+    let maybe_tokens = tokens::strings_to_tokens(token_strings);
     let maybe_ast = syntax_tree::tokens_to_ast(maybe_tokens);
     evaluate_ast(maybe_ast)
 }
@@ -56,11 +56,7 @@ fn print_expr_error(expr_error: &str) -> ! {
 }
 
 fn evaluate_ast(maybe_ast: Result<Box<syntax_tree::AstNode>, String>) -> Result<String, String> {
-    if maybe_ast.is_err() {
-        Err(maybe_ast.err().unwrap())
-    } else {
-        maybe_ast.ok().unwrap().evaluate()
-    }
+    maybe_ast.and_then(|ast| ast.evaluate())
 }
 
 fn maybe_handle_help_or_version(args: &[String]) -> bool {
diff --git a/src/uu/expr/src/syntax_tree.rs b/src/uu/expr/src/syntax_tree.rs
index b72d78729..ff49ea57e 100644
--- a/src/uu/expr/src/syntax_tree.rs
+++ b/src/uu/expr/src/syntax_tree.rs
@@ -160,10 +160,8 @@ impl AstNode {
         if let AstNode::Node { operands, .. } = self {
             let mut out = Vec::with_capacity(operands.len());
             for operand in operands {
-                match operand.evaluate() {
-                    Ok(value) => out.push(value),
-                    Err(reason) => return Err(reason),
-                }
+                let value = operand.evaluate()?;
+                out.push(value);
             }
             Ok(out)
         } else {
@@ -175,23 +173,14 @@ impl AstNode {
 pub fn tokens_to_ast(
     maybe_tokens: Result<Vec<(usize, Token)>, String>,
 ) -> Result<Box<AstNode>, String> {
-    if maybe_tokens.is_err() {
-        Err(maybe_tokens.err().unwrap())
-    } else {
-        let tokens = maybe_tokens.ok().unwrap();
+    maybe_tokens.and_then(|tokens| {
         let mut out_stack: TokenStack = Vec::new();
         let mut op_stack: TokenStack = Vec::new();
 
         for (token_idx, token) in tokens {
-            if let Err(reason) =
-                push_token_to_either_stack(token_idx, &token, &mut out_stack, &mut op_stack)
-            {
-                return Err(reason);
-            }
-        }
-        if let Err(reason) = move_rest_of_ops_to_out(&mut out_stack, &mut op_stack) {
-            return Err(reason);
+            push_token_to_either_stack(token_idx, &token, &mut out_stack, &mut op_stack)?;
         }
+        move_rest_of_ops_to_out(&mut out_stack, &mut op_stack)?;
         assert!(op_stack.is_empty());
 
         maybe_dump_rpn(&out_stack);
@@ -205,7 +194,7 @@ pub fn tokens_to_ast(
             maybe_dump_ast(&result);
             result
         }
-    }
+    })
 }
 
 fn maybe_dump_ast(result: &Result<Box<AstNode>, String>) {
@@ -261,10 +250,8 @@ fn maybe_ast_node(
 ) -> Result<Box<AstNode>, String> {
     let mut operands = Vec::with_capacity(arity);
     for _ in 0..arity {
-        match ast_from_rpn(rpn) {
-            Err(reason) => return Err(reason),
-            Ok(operand) => operands.push(operand),
-        }
+        let operand = ast_from_rpn(rpn)?;
+        operands.push(operand);
     }
     operands.reverse();
     Ok(AstNode::new_node(token_idx, op_type, operands))
@@ -408,10 +395,12 @@ fn move_till_match_paren(
     op_stack: &mut TokenStack,
 ) -> Result<(), String> {
     loop {
-        match op_stack.pop() {
-            None => return Err("syntax error (Mismatched close-parenthesis)".to_string()),
-            Some((_, Token::ParOpen)) => return Ok(()),
-            Some(other) => out_stack.push(other),
+        let op = op_stack
+            .pop()
+            .ok_or_else(|| "syntax error (Mismatched close-parenthesis)".to_string())?;
+        match op {
+            (_, Token::ParOpen) => return Ok(()),
+            other => out_stack.push(other),
         }
     }
 }
@@ -471,22 +460,17 @@ fn infix_operator_and(values: &[String]) -> String {
 
 fn operator_match(values: &[String]) -> Result<String, String> {
     assert!(values.len() == 2);
-    let re = match Regex::with_options(&values[1], RegexOptions::REGEX_OPTION_NONE, Syntax::grep())
-    {
-        Ok(m) => m,
-        Err(err) => return Err(err.description().to_string()),
-    };
-    if re.captures_len() > 0 {
-        Ok(match re.captures(&values[0]) {
-            Some(captures) => captures.at(1).unwrap().to_string(),
-            None => "".to_string(),
-        })
+    let re = Regex::with_options(&values[1], RegexOptions::REGEX_OPTION_NONE, Syntax::grep())
+        .map_err(|err| err.description().to_string())?;
+    Ok(if re.captures_len() > 0 {
+        re.captures(&values[0])
+            .map(|captures| captures.at(1).unwrap())
+            .unwrap_or("")
+            .to_string()
     } else {
-        Ok(match re.find(&values[0]) {
-            Some((start, end)) => (end - start).to_string(),
-            None => "0".to_string(),
-        })
-    }
+        re.find(&values[0])
+            .map_or("0".to_string(), |(start, end)| (end - start).to_string())
+    })
 }
 
 fn prefix_operator_length(values: &[String]) -> String {
diff --git a/src/uu/expr/src/tokens.rs b/src/uu/expr/src/tokens.rs
index 6f2795588..748960bc3 100644
--- a/src/uu/expr/src/tokens.rs
+++ b/src/uu/expr/src/tokens.rs
@@ -78,27 +78,27 @@ pub fn strings_to_tokens(strings: &[String]) -> Result<Vec<(usize, Token)>, Stri
             "(" => Token::ParOpen,
             ")" => Token::ParClose,
 
-            "^" => Token::new_infix_op(&s, false, 7),
+            "^" => Token::new_infix_op(s, false, 7),
 
-            ":" => Token::new_infix_op(&s, true, 6),
+            ":" => Token::new_infix_op(s, true, 6),
 
-            "*" => Token::new_infix_op(&s, true, 5),
-            "/" => Token::new_infix_op(&s, true, 5),
-            "%" => Token::new_infix_op(&s, true, 5),
+            "*" => Token::new_infix_op(s, true, 5),
+            "/" => Token::new_infix_op(s, true, 5),
+            "%" => Token::new_infix_op(s, true, 5),
 
-            "+" => Token::new_infix_op(&s, true, 4),
-            "-" => Token::new_infix_op(&s, true, 4),
+            "+" => Token::new_infix_op(s, true, 4),
+            "-" => Token::new_infix_op(s, true, 4),
 
-            "=" => Token::new_infix_op(&s, true, 3),
-            "!=" => Token::new_infix_op(&s, true, 3),
-            "<" => Token::new_infix_op(&s, true, 3),
-            ">" => Token::new_infix_op(&s, true, 3),
-            "<=" => Token::new_infix_op(&s, true, 3),
-            ">=" => Token::new_infix_op(&s, true, 3),
+            "=" => Token::new_infix_op(s, true, 3),
+            "!=" => Token::new_infix_op(s, true, 3),
+            "<" => Token::new_infix_op(s, true, 3),
+            ">" => Token::new_infix_op(s, true, 3),
+            "<=" => Token::new_infix_op(s, true, 3),
+            ">=" => Token::new_infix_op(s, true, 3),
 
-            "&" => Token::new_infix_op(&s, true, 2),
+            "&" => Token::new_infix_op(s, true, 2),
 
-            "|" => Token::new_infix_op(&s, true, 1),
+            "|" => Token::new_infix_op(s, true, 1),
 
             "match" => Token::PrefixOp {
                 arity: 2,
@@ -117,9 +117,9 @@ pub fn strings_to_tokens(strings: &[String]) -> Result<Vec<(usize, Token)>, Stri
                 value: s.clone(),
             },
 
-            _ => Token::new_value(&s),
+            _ => Token::new_value(s),
         };
-        push_token_if_not_escaped(&mut tokens_acc, tok_idx, token_if_not_escaped, &s);
+        push_token_if_not_escaped(&mut tokens_acc, tok_idx, token_if_not_escaped, s);
         tok_idx += 1;
     }
     maybe_dump_tokens_acc(&tokens_acc);
diff --git a/src/uu/fold/src/fold.rs b/src/uu/fold/src/fold.rs
index e476fed5b..118f7f5f9 100644
--- a/src/uu/fold/src/fold.rs
+++ b/src/uu/fold/src/fold.rs
@@ -98,7 +98,7 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
 fn handle_obsolete(args: &[String]) -> (Vec<String>, Option<String>) {
     for (i, arg) in args.iter().enumerate() {
         let slice = &arg;
-        if slice.starts_with('-') && slice.len() > 1 && slice.chars().nth(1).unwrap().is_digit(10) {
+        if slice.starts_with('-') && slice.chars().nth(1).map_or(false, |c| c.is_digit(10)) {
             let mut v = args.to_vec();
             v.remove(i);
             return (v, Some(slice[1..].to_owned()));
@@ -109,7 +109,7 @@ fn handle_obsolete(args: &[String]) -> (Vec<String>, Option<String>) {
 
 fn fold(filenames: Vec<String>, bytes: bool, spaces: bool, width: usize) {
     for filename in &filenames {
-        let filename: &str = &filename;
+        let filename: &str = filename;
         let mut stdin_buf;
         let mut file_buf;
         let buffer = BufReader::new(if filename == "-" {
diff --git a/src/uu/groups/Cargo.toml b/src/uu/groups/Cargo.toml
index 1a56bc2ab..4a5a537e5 100644
--- a/src/uu/groups/Cargo.toml
+++ b/src/uu/groups/Cargo.toml
@@ -15,7 +15,7 @@ edition = "2018"
 path = "src/groups.rs"
 
 [dependencies]
-uucore = { version=">=0.0.8", package="uucore", path="../../uucore", features=["entries"] }
+uucore = { version=">=0.0.8", package="uucore", path="../../uucore", features=["entries", "process"] }
 uucore_procs = { version=">=0.0.5", package="uucore_procs", path="../../uucore_procs" }
 clap = "2.33"
 
diff --git a/src/uu/hashsum/src/digest.rs b/src/uu/hashsum/src/digest.rs
index 25bc7f4c3..9093d94a7 100644
--- a/src/uu/hashsum/src/digest.rs
+++ b/src/uu/hashsum/src/digest.rs
@@ -59,7 +59,7 @@ impl Digest for blake2b_simd::State {
 
     fn result(&mut self, out: &mut [u8]) {
         let hash_result = &self.finalize();
-        out.copy_from_slice(&hash_result.as_bytes());
+        out.copy_from_slice(hash_result.as_bytes());
     }
 
     fn reset(&mut self) {
diff --git a/src/uu/hashsum/src/hashsum.rs b/src/uu/hashsum/src/hashsum.rs
index 9822ca3fa..a007473ab 100644
--- a/src/uu/hashsum/src/hashsum.rs
+++ b/src/uu/hashsum/src/hashsum.rs
@@ -90,7 +90,7 @@ fn detect_algo<'a>(
             512,
         ),
         "sha3sum" => match matches.value_of("bits") {
-            Some(bits_str) => match (&bits_str).parse::<usize>() {
+            Some(bits_str) => match (bits_str).parse::<usize>() {
                 Ok(224) => (
                     "SHA3-224",
                     Box::new(Sha3_224::new()) as Box<dyn Digest>,
@@ -140,7 +140,7 @@ fn detect_algo<'a>(
             512,
         ),
         "shake128sum" => match matches.value_of("bits") {
-            Some(bits_str) => match (&bits_str).parse::<usize>() {
+            Some(bits_str) => match (bits_str).parse::<usize>() {
                 Ok(bits) => (
                     "SHAKE128",
                     Box::new(Shake128::new()) as Box<dyn Digest>,
@@ -151,7 +151,7 @@ fn detect_algo<'a>(
             None => crash!(1, "--bits required for SHAKE-128"),
         },
         "shake256sum" => match matches.value_of("bits") {
-            Some(bits_str) => match (&bits_str).parse::<usize>() {
+            Some(bits_str) => match (bits_str).parse::<usize>() {
                 Ok(bits) => (
                     "SHAKE256",
                     Box::new(Shake256::new()) as Box<dyn Digest>,
@@ -194,7 +194,7 @@ fn detect_algo<'a>(
                 }
                 if matches.is_present("sha3") {
                     match matches.value_of("bits") {
-                        Some(bits_str) => match (&bits_str).parse::<usize>() {
+                        Some(bits_str) => match (bits_str).parse::<usize>() {
                             Ok(224) => set_or_crash(
                                 "SHA3-224",
                                 Box::new(Sha3_224::new()) as Box<dyn Digest>,
@@ -238,7 +238,7 @@ fn detect_algo<'a>(
                 }
                 if matches.is_present("shake128") {
                     match matches.value_of("bits") {
-                        Some(bits_str) => match (&bits_str).parse::<usize>() {
+                        Some(bits_str) => match (bits_str).parse::<usize>() {
                             Ok(bits) => set_or_crash("SHAKE128", Box::new(Shake128::new()), bits),
                             Err(err) => crash!(1, "{}", err),
                         },
@@ -247,7 +247,7 @@ fn detect_algo<'a>(
                 }
                 if matches.is_present("shake256") {
                     match matches.value_of("bits") {
-                        Some(bits_str) => match (&bits_str).parse::<usize>() {
+                        Some(bits_str) => match (bits_str).parse::<usize>() {
                             Ok(bits) => set_or_crash("SHAKE256", Box::new(Shake256::new()), bits),
                             Err(err) => crash!(1, "{}", err),
                         },
@@ -255,10 +255,8 @@ fn detect_algo<'a>(
                     }
                 }
             }
-            if alg.is_none() {
-                crash!(1, "You must specify hash algorithm!")
-            };
-            (name, alg.unwrap(), output_bits)
+            let alg = alg.unwrap_or_else(|| crash!(1, "You must specify hash algorithm!"));
+            (name, alg, output_bits)
         }
     }
 }
diff --git a/src/uu/head/src/head.rs b/src/uu/head/src/head.rs
index 28710e1fe..aceecd941 100644
--- a/src/uu/head/src/head.rs
+++ b/src/uu/head/src/head.rs
@@ -1,3 +1,8 @@
+//  * This file is part of the uutils coreutils package.
+//  *
+//  * For the full copyright and license information, please view the LICENSE
+//  * file that was distributed with this source code.
+
 // spell-checker:ignore (vars) zlines
 
 use clap::{crate_version, App, Arg};
@@ -75,7 +80,7 @@ fn app<'a>() -> App<'a, 'a> {
         .arg(
             Arg::with_name(options::QUIET_NAME)
                 .short("q")
-                .long("--quiet")
+                .long("quiet")
                 .visible_alias("silent")
                 .help("never print headers giving file names")
                 .overrides_with_all(&[options::VERBOSE_NAME, options::QUIET_NAME]),
@@ -108,12 +113,7 @@ where
 {
     match parse::parse_num(src) {
         Ok((n, last)) => Ok((closure(n), last)),
-        Err(reason) => match reason {
-            parse::ParseError::Syntax => Err(format!("'{}'", src)),
-            parse::ParseError::Overflow => {
-                Err(format!("'{}': Value too large for defined datatype", src))
-            }
-        },
+        Err(e) => Err(e.to_string()),
     }
 }
 
@@ -176,19 +176,11 @@ impl HeadOptions {
         options.zeroed = matches.is_present(options::ZERO_NAME);
 
         let mode_and_from_end = if let Some(v) = matches.value_of(options::BYTES_NAME) {
-            match parse_mode(v, Modes::Bytes) {
-                Ok(v) => v,
-                Err(err) => {
-                    return Err(format!("invalid number of bytes: {}", err));
-                }
-            }
+            parse_mode(v, Modes::Bytes)
+                .map_err(|err| format!("invalid number of bytes: {}", err))?
         } else if let Some(v) = matches.value_of(options::LINES_NAME) {
-            match parse_mode(v, Modes::Lines) {
-                Ok(v) => v,
-                Err(err) => {
-                    return Err(format!("invalid number of lines: {}", err));
-                }
-            }
+            parse_mode(v, Modes::Lines)
+                .map_err(|err| format!("invalid number of lines: {}", err))?
         } else {
             (Modes::Lines(10), false)
         };
@@ -474,7 +466,7 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
     let args = match HeadOptions::get_from(args) {
         Ok(o) => o,
         Err(s) => {
-            crash!(EXIT_FAILURE, "head: {}", s);
+            crash!(EXIT_FAILURE, "{}", s);
         }
     };
     match uu_head(&args) {
diff --git a/src/uu/head/src/parse.rs b/src/uu/head/src/parse.rs
index f1c97561d..f6f291814 100644
--- a/src/uu/head/src/parse.rs
+++ b/src/uu/head/src/parse.rs
@@ -1,5 +1,10 @@
-use std::convert::TryFrom;
+//  * This file is part of the uutils coreutils package.
+//  *
+//  * For the full copyright and license information, please view the LICENSE
+//  * file that was distributed with this source code.
+
 use std::ffi::OsString;
+use uucore::parse_size::{parse_size, ParseSizeError};
 
 #[derive(PartialEq, Debug)]
 pub enum ParseError {
@@ -92,92 +97,25 @@ pub fn parse_obsolete(src: &str) -> Option<Result<impl Iterator<Item = OsString>
 }
 /// Parses an -c or -n argument,
 /// the bool specifies whether to read from the end
-pub fn parse_num(src: &str) -> Result<(usize, bool), ParseError> {
-    let mut num_start = 0;
-    let mut chars = src.char_indices();
-    let (mut chars, all_but_last) = match chars.next() {
-        Some((_, c)) => {
+pub fn parse_num(src: &str) -> Result<(usize, bool), ParseSizeError> {
+    let mut size_string = src.trim();
+    let mut all_but_last = false;
+
+    if let Some(c) = size_string.chars().next() {
+        if c == '+' || c == '-' {
+            // head: '+' is not documented (8.32 man pages)
+            size_string = &size_string[1..];
             if c == '-' {
-                num_start += 1;
-                (chars, true)
-            } else {
-                (src.char_indices(), false)
+                all_but_last = true;
             }
         }
-        None => return Err(ParseError::Syntax),
-    };
-    let mut num_end = 0usize;
-    let mut last_char = 0 as char;
-    let mut num_count = 0usize;
-    for (n, c) in &mut chars {
-        if c.is_numeric() {
-            num_end = n;
-            num_count += 1;
-        } else {
-            last_char = c;
-            break;
-        }
+    } else {
+        return Err(ParseSizeError::ParseFailure(src.to_string()));
     }
 
-    let num = if num_count > 0 {
-        match src[num_start..=num_end].parse::<usize>() {
-            Ok(n) => Some(n),
-            Err(_) => return Err(ParseError::Overflow),
-        }
-    } else {
-        None
-    };
-
-    if last_char == 0 as char {
-        if let Some(n) = num {
-            Ok((n, all_but_last))
-        } else {
-            Err(ParseError::Syntax)
-        }
-    } else {
-        let base: u128 = match chars.next() {
-            Some((_, c)) => {
-                let b = match c {
-                    'B' if last_char != 'b' => 1000,
-                    'i' if last_char != 'b' => {
-                        if let Some((_, 'B')) = chars.next() {
-                            1024
-                        } else {
-                            return Err(ParseError::Syntax);
-                        }
-                    }
-                    _ => return Err(ParseError::Syntax),
-                };
-                if chars.next().is_some() {
-                    return Err(ParseError::Syntax);
-                } else {
-                    b
-                }
-            }
-            None => 1024,
-        };
-        let mul = match last_char.to_lowercase().next().unwrap() {
-            'b' => 512,
-            'k' => base.pow(1),
-            'm' => base.pow(2),
-            'g' => base.pow(3),
-            't' => base.pow(4),
-            'p' => base.pow(5),
-            'e' => base.pow(6),
-            'z' => base.pow(7),
-            'y' => base.pow(8),
-            _ => return Err(ParseError::Syntax),
-        };
-        let mul = match usize::try_from(mul) {
-            Ok(n) => n,
-            Err(_) => return Err(ParseError::Overflow),
-        };
-        match num.unwrap_or(1).checked_mul(mul) {
-            Some(n) => Ok((n, all_but_last)),
-            None => Err(ParseError::Overflow),
-        }
-    }
+    parse_size(size_string).map(|n| (n, all_but_last))
 }
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -195,44 +133,6 @@ mod tests {
         Some(Ok(src.iter().map(|s| s.to_string()).collect()))
     }
     #[test]
-    #[cfg(not(target_pointer_width = "128"))]
-    fn test_parse_overflow_x64() {
-        assert_eq!(parse_num("1Y"), Err(ParseError::Overflow));
-        assert_eq!(parse_num("1Z"), Err(ParseError::Overflow));
-        assert_eq!(parse_num("100E"), Err(ParseError::Overflow));
-        assert_eq!(parse_num("100000P"), Err(ParseError::Overflow));
-        assert_eq!(parse_num("1000000000T"), Err(ParseError::Overflow));
-        assert_eq!(
-            parse_num("10000000000000000000000"),
-            Err(ParseError::Overflow)
-        );
-    }
-    #[test]
-    #[cfg(target_pointer_width = "32")]
-    fn test_parse_overflow_x32() {
-        assert_eq!(parse_num("1T"), Err(ParseError::Overflow));
-        assert_eq!(parse_num("1000G"), Err(ParseError::Overflow));
-    }
-    #[test]
-    fn test_parse_bad_syntax() {
-        assert_eq!(parse_num("5MiB nonsense"), Err(ParseError::Syntax));
-        assert_eq!(parse_num("Nonsense string"), Err(ParseError::Syntax));
-        assert_eq!(parse_num("5mib"), Err(ParseError::Syntax));
-        assert_eq!(parse_num("biB"), Err(ParseError::Syntax));
-        assert_eq!(parse_num("-"), Err(ParseError::Syntax));
-        assert_eq!(parse_num(""), Err(ParseError::Syntax));
-    }
-    #[test]
-    fn test_parse_numbers() {
-        assert_eq!(parse_num("k"), Ok((1024, false)));
-        assert_eq!(parse_num("MiB"), Ok((1024 * 1024, false)));
-        assert_eq!(parse_num("-5"), Ok((5, true)));
-        assert_eq!(parse_num("b"), Ok((512, false)));
-        assert_eq!(parse_num("-2GiB"), Ok((2 * 1024 * 1024 * 1024, true)));
-        assert_eq!(parse_num("5M"), Ok((5 * 1024 * 1024, false)));
-        assert_eq!(parse_num("5MB"), Ok((5 * 1000 * 1000, false)));
-    }
-    #[test]
     fn test_parse_numbers_obsolete() {
         assert_eq!(obsolete("-5"), obsolete_result(&["-n", "5"]));
         assert_eq!(obsolete("-100"), obsolete_result(&["-n", "100"]));
diff --git a/src/uu/install/src/install.rs b/src/uu/install/src/install.rs
index 7aa6f95ff..ad5ea694c 100644
--- a/src/uu/install/src/install.rs
+++ b/src/uu/install/src/install.rs
@@ -299,29 +299,17 @@ fn behavior(matches: &ArgMatches) -> Result<Behavior, i32> {
     let considering_dir: bool = MainFunction::Directory == main_function;
 
     let specified_mode: Option<u32> = if matches.is_present(OPT_MODE) {
-        match matches.value_of(OPT_MODE) {
-            Some(x) => match mode::parse(x, considering_dir) {
-                Ok(y) => Some(y),
-                Err(err) => {
-                    show_error!("Invalid mode string: {}", err);
-                    return Err(1);
-                }
-            },
-            None => {
-                return Err(1);
-            }
-        }
+        let x = matches.value_of(OPT_MODE).ok_or(1)?;
+        Some(mode::parse(x, considering_dir).map_err(|err| {
+            show_error!("Invalid mode string: {}", err);
+            1
+        })?)
     } else {
         None
     };
 
     let backup_suffix = if matches.is_present(OPT_SUFFIX) {
-        match matches.value_of(OPT_SUFFIX) {
-            Some(x) => x,
-            None => {
-                return Err(1);
-            }
-        }
+        matches.value_of(OPT_SUFFIX).ok_or(1)?
     } else {
         "~"
     };
@@ -379,7 +367,7 @@ fn directory(paths: Vec<String>, b: Behavior) -> i32 {
                 }
             }
 
-            if mode::chmod(&path, b.mode()).is_err() {
+            if mode::chmod(path, b.mode()).is_err() {
                 all_successful = false;
                 continue;
             }
@@ -422,7 +410,7 @@ fn standard(paths: Vec<String>, b: Behavior) -> i32 {
                     return 1;
                 }
 
-                if mode::chmod(&parent, b.mode()).is_err() {
+                if mode::chmod(parent, b.mode()).is_err() {
                     show_error!("failed to chmod {}", parent.display());
                     return 1;
                 }
@@ -501,7 +489,7 @@ fn copy_files_into_dir(files: &[PathBuf], target_dir: &Path, b: &Behavior) -> i3
 /// _target_ must be a non-directory
 ///
 fn copy_file_to_file(file: &Path, target: &Path, b: &Behavior) -> i32 {
-    if copy(file, &target, b).is_err() {
+    if copy(file, target, b).is_err() {
         1
     } else {
         0
@@ -563,7 +551,7 @@ fn copy(from: &Path, to: &Path, b: &Behavior) -> Result<(), ()> {
         }
     }
 
-    if mode::chmod(&to, b.mode()).is_err() {
+    if mode::chmod(to, b.mode()).is_err() {
         return Err(());
     }
 
diff --git a/src/uu/join/src/join.rs b/src/uu/join/src/join.rs
index 7a044789f..4cdfe2141 100644
--- a/src/uu/join/src/join.rs
+++ b/src/uu/join/src/join.rs
@@ -328,8 +328,8 @@ impl<'a> State<'a> {
                     });
                 } else {
                     repr.print_field(key);
-                    repr.print_fields(&line1, self.key, self.max_fields);
-                    repr.print_fields(&line2, other.key, other.max_fields);
+                    repr.print_fields(line1, self.key, self.max_fields);
+                    repr.print_fields(line2, other.key, other.max_fields);
                 }
 
                 println!();
@@ -611,7 +611,7 @@ fn exec(file1: &str, file2: &str, settings: &Settings) -> i32 {
 
     let mut state1 = State::new(
         FileNum::File1,
-        &file1,
+        file1,
         &stdin,
         settings.key1,
         settings.print_unpaired,
@@ -619,7 +619,7 @@ fn exec(file1: &str, file2: &str, settings: &Settings) -> i32 {
 
     let mut state2 = State::new(
         FileNum::File2,
-        &file2,
+        file2,
         &stdin,
         settings.key2,
         settings.print_unpaired,
diff --git a/src/uu/kill/src/kill.rs b/src/uu/kill/src/kill.rs
index 6c2464c92..a49acaa05 100644
--- a/src/uu/kill/src/kill.rs
+++ b/src/uu/kill/src/kill.rs
@@ -111,7 +111,7 @@ fn handle_obsolete(mut args: Vec<String>) -> (Vec<String>, Option<String>) {
     while i < args.len() {
         // this is safe because slice is valid when it is referenced
         let slice = &args[i].clone();
-        if slice.starts_with('-') && slice.len() > 1 && slice.chars().nth(1).unwrap().is_digit(10) {
+        if slice.starts_with('-') && slice.chars().nth(1).map_or(false, |c| c.is_digit(10)) {
             let val = &slice[1..];
             match val.parse() {
                 Ok(num) => {
diff --git a/src/uu/ln/src/ln.rs b/src/uu/ln/src/ln.rs
index cd5eef842..ce1dd15b0 100644
--- a/src/uu/ln/src/ln.rs
+++ b/src/uu/ln/src/ln.rs
@@ -27,7 +27,6 @@ use uucore::fs::{canonicalize, CanonicalizeMode};
 pub struct Settings {
     overwrite: OverwriteMode,
     backup: BackupMode,
-    force: bool,
     suffix: String,
     symbolic: bool,
     relative: bool,
@@ -54,7 +53,7 @@ pub enum BackupMode {
 
 fn get_usage() -> String {
     format!(
-        "{0} [OPTION]... [-T] TARGET LINK_executable!()   (1st form)
+        "{0} [OPTION]... [-T] TARGET LINK_NAME   (1st form)
        {0} [OPTION]... TARGET                  (2nd form)
        {0} [OPTION]... TARGET... DIRECTORY     (3rd form)
        {0} [OPTION]... -t DIRECTORY TARGET...  (4th form)",
@@ -64,7 +63,7 @@ fn get_usage() -> String {
 
 fn get_long_usage() -> String {
     String::from(
-        " In the 1st form, create a link to TARGET with the name LINK_executable!().
+        " In the 1st form, create a link to TARGET with the name LINK_NAME.
         In the 2nd form, create a link to TARGET in the current directory.
         In the 3rd and 4th forms, create links to each TARGET in DIRECTORY.
         Create hard links by default, symbolic links with --symbolic.
@@ -78,17 +77,19 @@ fn get_long_usage() -> String {
 
 static ABOUT: &str = "change file owner and group";
 
-static OPT_B: &str = "b";
-static OPT_BACKUP: &str = "backup";
-static OPT_FORCE: &str = "force";
-static OPT_INTERACTIVE: &str = "interactive";
-static OPT_NO_DEREFERENCE: &str = "no-dereference";
-static OPT_SYMBOLIC: &str = "symbolic";
-static OPT_SUFFIX: &str = "suffix";
-static OPT_TARGET_DIRECTORY: &str = "target-directory";
-static OPT_NO_TARGET_DIRECTORY: &str = "no-target-directory";
-static OPT_RELATIVE: &str = "relative";
-static OPT_VERBOSE: &str = "verbose";
+mod options {
+    pub const B: &str = "b";
+    pub const BACKUP: &str = "backup";
+    pub const FORCE: &str = "force";
+    pub const INTERACTIVE: &str = "interactive";
+    pub const NO_DEREFERENCE: &str = "no-dereference";
+    pub const SYMBOLIC: &str = "symbolic";
+    pub const SUFFIX: &str = "suffix";
+    pub const TARGET_DIRECTORY: &str = "target-directory";
+    pub const NO_TARGET_DIRECTORY: &str = "no-target-directory";
+    pub const RELATIVE: &str = "relative";
+    pub const VERBOSE: &str = "verbose";
+}
 
 static ARG_FILES: &str = "files";
 
@@ -101,49 +102,44 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
         .about(ABOUT)
         .usage(&usage[..])
         .after_help(&long_usage[..])
-        .arg(Arg::with_name(OPT_B).short(OPT_B).help(
+        .arg(Arg::with_name(options::B).short(options::B).help(
             "make a backup of each file that would otherwise be overwritten or \
              removed",
         ))
         .arg(
-            Arg::with_name(OPT_BACKUP)
-                .long(OPT_BACKUP)
+            Arg::with_name(options::BACKUP)
+                .long(options::BACKUP)
                 .help(
                     "make a backup of each file that would otherwise be overwritten \
                      or removed",
                 )
                 .takes_value(true)
-                .possible_value("simple")
-                .possible_value("never")
-                .possible_value("numbered")
-                .possible_value("t")
-                .possible_value("existing")
-                .possible_value("nil")
-                .possible_value("none")
-                .possible_value("off")
+                .possible_values(&[
+                    "simple", "never", "numbered", "t", "existing", "nil", "none", "off",
+                ])
                 .value_name("METHOD"),
         )
         // TODO: opts.arg(
         //    Arg::with_name(("d", "directory", "allow users with appropriate privileges to attempt \
         //                                       to make hard links to directories");
         .arg(
-            Arg::with_name(OPT_FORCE)
+            Arg::with_name(options::FORCE)
                 .short("f")
-                .long(OPT_FORCE)
+                .long(options::FORCE)
                 .help("remove existing destination files"),
         )
         .arg(
-            Arg::with_name(OPT_INTERACTIVE)
+            Arg::with_name(options::INTERACTIVE)
                 .short("i")
-                .long(OPT_INTERACTIVE)
+                .long(options::INTERACTIVE)
                 .help("prompt whether to remove existing destination files"),
         )
         .arg(
-            Arg::with_name(OPT_NO_DEREFERENCE)
+            Arg::with_name(options::NO_DEREFERENCE)
                 .short("n")
-                .long(OPT_NO_DEREFERENCE)
+                .long(options::NO_DEREFERENCE)
                 .help(
-                    "treat LINK_executable!() as a normal file if it is a \
+                    "treat LINK_NAME as a normal file if it is a \
                      symbolic link to a directory",
                 ),
         )
@@ -153,43 +149,46 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
         // TODO: opts.arg(
         //    Arg::with_name(("P", "physical", "make hard links directly to symbolic links");
         .arg(
-            Arg::with_name(OPT_SYMBOLIC)
+            Arg::with_name(options::SYMBOLIC)
                 .short("s")
                 .long("symbolic")
-                .help("make symbolic links instead of hard links"),
+                .help("make symbolic links instead of hard links")
+                // override added for https://github.com/uutils/coreutils/issues/2359
+                .overrides_with(options::SYMBOLIC),
         )
         .arg(
-            Arg::with_name(OPT_SUFFIX)
+            Arg::with_name(options::SUFFIX)
                 .short("S")
-                .long(OPT_SUFFIX)
+                .long(options::SUFFIX)
                 .help("override the usual backup suffix")
                 .value_name("SUFFIX")
                 .takes_value(true),
         )
         .arg(
-            Arg::with_name(OPT_TARGET_DIRECTORY)
+            Arg::with_name(options::TARGET_DIRECTORY)
                 .short("t")
-                .long(OPT_TARGET_DIRECTORY)
+                .long(options::TARGET_DIRECTORY)
                 .help("specify the DIRECTORY in which to create the links")
                 .value_name("DIRECTORY")
-                .conflicts_with(OPT_NO_TARGET_DIRECTORY),
+                .conflicts_with(options::NO_TARGET_DIRECTORY),
         )
         .arg(
-            Arg::with_name(OPT_NO_TARGET_DIRECTORY)
+            Arg::with_name(options::NO_TARGET_DIRECTORY)
                 .short("T")
-                .long(OPT_NO_TARGET_DIRECTORY)
-                .help("treat LINK_executable!() as a normal file always"),
+                .long(options::NO_TARGET_DIRECTORY)
+                .help("treat LINK_NAME as a normal file always"),
         )
         .arg(
-            Arg::with_name(OPT_RELATIVE)
+            Arg::with_name(options::RELATIVE)
                 .short("r")
-                .long(OPT_RELATIVE)
-                .help("create symbolic links relative to link location"),
+                .long(options::RELATIVE)
+                .help("create symbolic links relative to link location")
+                .requires(options::SYMBOLIC),
         )
         .arg(
-            Arg::with_name(OPT_VERBOSE)
+            Arg::with_name(options::VERBOSE)
                 .short("v")
-                .long(OPT_VERBOSE)
+                .long(options::VERBOSE)
                 .help("print name of each linked file"),
         )
         .arg(
@@ -209,18 +208,18 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
         .map(PathBuf::from)
         .collect();
 
-    let overwrite_mode = if matches.is_present(OPT_FORCE) {
+    let overwrite_mode = if matches.is_present(options::FORCE) {
         OverwriteMode::Force
-    } else if matches.is_present(OPT_INTERACTIVE) {
+    } else if matches.is_present(options::INTERACTIVE) {
         OverwriteMode::Interactive
     } else {
         OverwriteMode::NoClobber
     };
 
-    let backup_mode = if matches.is_present(OPT_B) {
+    let backup_mode = if matches.is_present(options::B) {
         BackupMode::ExistingBackup
-    } else if matches.is_present(OPT_BACKUP) {
-        match matches.value_of(OPT_BACKUP) {
+    } else if matches.is_present(options::BACKUP) {
+        match matches.value_of(options::BACKUP) {
             None => BackupMode::ExistingBackup,
             Some(mode) => match mode {
                 "simple" | "never" => BackupMode::SimpleBackup,
@@ -234,8 +233,8 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
         BackupMode::NoBackup
     };
 
-    let backup_suffix = if matches.is_present(OPT_SUFFIX) {
-        matches.value_of(OPT_SUFFIX).unwrap()
+    let backup_suffix = if matches.is_present(options::SUFFIX) {
+        matches.value_of(options::SUFFIX).unwrap()
     } else {
         "~"
     };
@@ -243,14 +242,15 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
     let settings = Settings {
         overwrite: overwrite_mode,
         backup: backup_mode,
-        force: matches.is_present(OPT_FORCE),
         suffix: backup_suffix.to_string(),
-        symbolic: matches.is_present(OPT_SYMBOLIC),
-        relative: matches.is_present(OPT_RELATIVE),
-        target_dir: matches.value_of(OPT_TARGET_DIRECTORY).map(String::from),
-        no_target_dir: matches.is_present(OPT_NO_TARGET_DIRECTORY),
-        no_dereference: matches.is_present(OPT_NO_DEREFERENCE),
-        verbose: matches.is_present(OPT_VERBOSE),
+        symbolic: matches.is_present(options::SYMBOLIC),
+        relative: matches.is_present(options::RELATIVE),
+        target_dir: matches
+            .value_of(options::TARGET_DIRECTORY)
+            .map(String::from),
+        no_target_dir: matches.is_present(options::NO_TARGET_DIRECTORY),
+        no_dereference: matches.is_present(options::NO_DEREFERENCE),
+        verbose: matches.is_present(options::VERBOSE),
     };
 
     exec(&paths[..], &settings)
@@ -260,17 +260,17 @@ fn exec(files: &[PathBuf], settings: &Settings) -> i32 {
     // Handle cases where we create links in a directory first.
     if let Some(ref name) = settings.target_dir {
         // 4th form: a directory is specified by -t.
-        return link_files_in_dir(files, &PathBuf::from(name), &settings);
+        return link_files_in_dir(files, &PathBuf::from(name), settings);
     }
     if !settings.no_target_dir {
         if files.len() == 1 {
             // 2nd form: the target directory is the current directory.
-            return link_files_in_dir(files, &PathBuf::from("."), &settings);
+            return link_files_in_dir(files, &PathBuf::from("."), settings);
         }
         let last_file = &PathBuf::from(files.last().unwrap());
         if files.len() > 2 || last_file.is_dir() {
             // 3rd form: create links in the last argument.
-            return link_files_in_dir(&files[0..files.len() - 1], last_file, &settings);
+            return link_files_in_dir(&files[0..files.len() - 1], last_file, settings);
         }
     }
 
@@ -310,47 +310,48 @@ fn link_files_in_dir(files: &[PathBuf], target_dir: &Path, settings: &Settings)
 
     let mut all_successful = true;
     for srcpath in files.iter() {
-        let targetpath = if settings.no_dereference && settings.force {
-            // In that case, we don't want to do link resolution
-            // We need to clean the target
-            if is_symlink(target_dir) {
-                if target_dir.is_file() {
-                    if let Err(e) = fs::remove_file(target_dir) {
-                        show_error!("Could not update {}: {}", target_dir.display(), e)
-                    };
-                }
-                if target_dir.is_dir() {
-                    // Not sure why but on Windows, the symlink can be
-                    // considered as a dir
-                    // See test_ln::test_symlink_no_deref_dir
-                    if let Err(e) = fs::remove_dir(target_dir) {
-                        show_error!("Could not update {}: {}", target_dir.display(), e)
-                    };
-                }
-            }
-            target_dir.to_path_buf()
-        } else {
-            match srcpath.as_os_str().to_str() {
-                Some(name) => {
-                    match Path::new(name).file_name() {
-                        Some(basename) => target_dir.join(basename),
-                        // This can be None only for "." or "..". Trying
-                        // to create a link with such name will fail with
-                        // EEXIST, which agrees with the behavior of GNU
-                        // coreutils.
-                        None => target_dir.join(name),
+        let targetpath =
+            if settings.no_dereference && matches!(settings.overwrite, OverwriteMode::Force) {
+                // In that case, we don't want to do link resolution
+                // We need to clean the target
+                if is_symlink(target_dir) {
+                    if target_dir.is_file() {
+                        if let Err(e) = fs::remove_file(target_dir) {
+                            show_error!("Could not update {}: {}", target_dir.display(), e)
+                        };
+                    }
+                    if target_dir.is_dir() {
+                        // Not sure why but on Windows, the symlink can be
+                        // considered as a dir
+                        // See test_ln::test_symlink_no_deref_dir
+                        if let Err(e) = fs::remove_dir(target_dir) {
+                            show_error!("Could not update {}: {}", target_dir.display(), e)
+                        };
                     }
                 }
-                None => {
-                    show_error!(
-                        "cannot stat '{}': No such file or directory",
-                        srcpath.display()
-                    );
-                    all_successful = false;
-                    continue;
+                target_dir.to_path_buf()
+            } else {
+                match srcpath.as_os_str().to_str() {
+                    Some(name) => {
+                        match Path::new(name).file_name() {
+                            Some(basename) => target_dir.join(basename),
+                            // This can be None only for "." or "..". Trying
+                            // to create a link with such name will fail with
+                            // EEXIST, which agrees with the behavior of GNU
+                            // coreutils.
+                            None => target_dir.join(name),
+                        }
+                    }
+                    None => {
+                        show_error!(
+                            "cannot stat '{}': No such file or directory",
+                            srcpath.display()
+                        );
+                        all_successful = false;
+                        continue;
+                    }
                 }
-            }
-        };
+            };
 
         if let Err(e) = link(srcpath, &targetpath, settings) {
             show_error!(
@@ -371,7 +372,8 @@ fn link_files_in_dir(files: &[PathBuf], target_dir: &Path, settings: &Settings)
 
 fn relative_path<'a>(src: &Path, dst: &Path) -> Result<Cow<'a, Path>> {
     let src_abs = canonicalize(src, CanonicalizeMode::Normal)?;
-    let dst_abs = canonicalize(dst, CanonicalizeMode::Normal)?;
+    let mut dst_abs = canonicalize(dst.parent().unwrap(), CanonicalizeMode::Normal)?;
+    dst_abs.push(dst.components().last().unwrap());
     let suffix_pos = src_abs
         .components()
         .zip(dst_abs.components())
@@ -392,7 +394,7 @@ fn relative_path<'a>(src: &Path, dst: &Path) -> Result<Cow<'a, Path>> {
 fn link(src: &Path, dst: &Path, settings: &Settings) -> Result<()> {
     let mut backup_path = None;
     let source: Cow<'_, Path> = if settings.relative {
-        relative_path(&src, dst)?
+        relative_path(src, dst)?
     } else {
         src.into()
     };
@@ -421,10 +423,6 @@ fn link(src: &Path, dst: &Path, settings: &Settings) -> Result<()> {
         }
     }
 
-    if settings.no_dereference && settings.force && dst.exists() {
-        fs::remove_file(dst)?;
-    }
-
     if settings.symbolic {
         symlink(&source, dst)?;
     } else {
diff --git a/src/uu/ls/src/ls.rs b/src/uu/ls/src/ls.rs
index 3c7b22360..dc67d5738 100644
--- a/src/uu/ls/src/ls.rs
+++ b/src/uu/ls/src/ls.rs
@@ -1243,7 +1243,7 @@ fn sort_entries(entries: &mut Vec<PathData>, config: &Config) {
         Sort::Time => entries.sort_by_key(|k| {
             Reverse(
                 k.md()
-                    .and_then(|md| get_system_time(&md, config))
+                    .and_then(|md| get_system_time(md, config))
                     .unwrap_or(UNIX_EPOCH),
             )
         }),
@@ -1323,7 +1323,7 @@ fn enter_directory(dir: &PathData, config: &Config, out: &mut BufWriter<Stdout>)
             .filter(|p| p.file_type().map(|ft| ft.is_dir()).unwrap_or(false))
         {
             let _ = writeln!(out, "\n{}:", e.p_buf.display());
-            enter_directory(&e, config, out);
+            enter_directory(e, config, out);
         }
     }
 }
@@ -1339,8 +1339,8 @@ fn get_metadata(entry: &Path, dereference: bool) -> std::io::Result<Metadata> {
 fn display_dir_entry_size(entry: &PathData, config: &Config) -> (usize, usize) {
     if let Some(md) = entry.md() {
         (
-            display_symlink_count(&md).len(),
-            display_size_or_rdev(&md, config).len(),
+            display_symlink_count(md).len(),
+            display_size_or_rdev(md, config).len(),
         )
     } else {
         (0, 0)
@@ -1371,7 +1371,7 @@ fn display_items(items: &[PathData], config: &Config, out: &mut BufWriter<Stdout
             display_item_long(item, max_links, max_width, config, out);
         }
     } else {
-        let names = items.iter().filter_map(|i| display_file_name(&i, config));
+        let names = items.iter().filter_map(|i| display_file_name(i, config));
 
         match (&config.format, config.width) {
             (Format::Columns, Some(width)) => {
@@ -1482,40 +1482,40 @@ fn display_item_long(
     #[cfg(unix)]
     {
         if config.inode {
-            let _ = write!(out, "{} ", get_inode(&md));
+            let _ = write!(out, "{} ", get_inode(md));
         }
     }
 
     let _ = write!(
         out,
         "{} {}",
-        display_permissions(&md, true),
-        pad_left(display_symlink_count(&md), max_links),
+        display_permissions(md, true),
+        pad_left(display_symlink_count(md), max_links),
     );
 
     if config.long.owner {
-        let _ = write!(out, " {}", display_uname(&md, config));
+        let _ = write!(out, " {}", display_uname(md, config));
     }
 
     if config.long.group {
-        let _ = write!(out, " {}", display_group(&md, config));
+        let _ = write!(out, " {}", display_group(md, config));
     }
 
     // Author is only different from owner on GNU/Hurd, so we reuse
     // the owner, since GNU/Hurd is not currently supported by Rust.
     if config.long.author {
-        let _ = write!(out, " {}", display_uname(&md, config));
+        let _ = write!(out, " {}", display_uname(md, config));
     }
 
     let _ = writeln!(
         out,
         " {} {} {}",
         pad_left(display_size_or_rdev(md, config), max_size),
-        display_date(&md, config),
+        display_date(md, config),
         // unwrap is fine because it fails when metadata is not available
         // but we already know that it is because it's checked at the
         // start of the function.
-        display_file_name(&item, config).unwrap().contents,
+        display_file_name(item, config).unwrap().contents,
     );
 }
 
@@ -1741,7 +1741,7 @@ fn display_file_name(path: &PathData, config: &Config) -> Option<Cell> {
     let mut width = name.width();
 
     if let Some(ls_colors) = &config.color {
-        name = color_name(&ls_colors, &path.p_buf, name, path.md()?);
+        name = color_name(ls_colors, &path.p_buf, name, path.md()?);
     }
 
     if config.indicator_style != IndicatorStyle::None {
@@ -1786,7 +1786,7 @@ fn display_file_name(path: &PathData, config: &Config) -> Option<Cell> {
 }
 
 fn color_name(ls_colors: &LsColors, path: &Path, name: String, md: &Metadata) -> String {
-    match ls_colors.style_for_path_with_metadata(path, Some(&md)) {
+    match ls_colors.style_for_path_with_metadata(path, Some(md)) {
         Some(style) => style.to_ansi_term_style().paint(name).to_string(),
         None => name,
     }
diff --git a/src/uu/mkdir/src/mkdir.rs b/src/uu/mkdir/src/mkdir.rs
index d1461c0c9..e8a8ef2db 100644
--- a/src/uu/mkdir/src/mkdir.rs
+++ b/src/uu/mkdir/src/mkdir.rs
@@ -77,7 +77,7 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
     let mode_match = matches.value_of(OPT_MODE);
     let mode: u16 = match mode_match {
         Some(m) => {
-            let res: Option<u16> = u16::from_str_radix(&m, 8).ok();
+            let res: Option<u16> = u16::from_str_radix(m, 8).ok();
             match res {
                 Some(r) => r,
                 _ => crash!(1, "no mode given"),
diff --git a/src/uu/mkfifo/src/mkfifo.rs b/src/uu/mkfifo/src/mkfifo.rs
index cf2fefa50..b8a6bbe38 100644
--- a/src/uu/mkfifo/src/mkfifo.rs
+++ b/src/uu/mkfifo/src/mkfifo.rs
@@ -59,7 +59,7 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
     }
 
     let mode = match matches.value_of(options::MODE) {
-        Some(m) => match usize::from_str_radix(&m, 8) {
+        Some(m) => match usize::from_str_radix(m, 8) {
             Ok(m) => m,
             Err(e) => {
                 show_error!("invalid mode: {}", e);
diff --git a/src/uu/mktemp/src/mktemp.rs b/src/uu/mktemp/src/mktemp.rs
index 67a88273d..e04de8702 100644
--- a/src/uu/mktemp/src/mktemp.rs
+++ b/src/uu/mktemp/src/mktemp.rs
@@ -165,9 +165,9 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
     };
 
     if dry_run {
-        dry_exec(tmpdir, prefix, rand, &suffix)
+        dry_exec(tmpdir, prefix, rand, suffix)
     } else {
-        exec(tmpdir, prefix, rand, &suffix, make_dir, suppress_file_err)
+        exec(tmpdir, prefix, rand, suffix, make_dir, suppress_file_err)
     }
 }
 
diff --git a/src/uu/more/Cargo.toml b/src/uu/more/Cargo.toml
index b3b97e6dd..af6781876 100644
--- a/src/uu/more/Cargo.toml
+++ b/src/uu/more/Cargo.toml
@@ -19,7 +19,7 @@ clap = "2.33"
 uucore = { version = ">=0.0.7", package = "uucore", path = "../../uucore" }
 uucore_procs = { version = ">=0.0.5", package = "uucore_procs", path = "../../uucore_procs" }
 crossterm = ">=0.19"
-atty = "0.2.14"
+atty = "0.2"
 unicode-width = "0.1.7"
 unicode-segmentation = "1.7.1"
 
diff --git a/src/uu/more/src/more.rs b/src/uu/more/src/more.rs
index 4d345e96b..206cebbc2 100644
--- a/src/uu/more/src/more.rs
+++ b/src/uu/more/src/more.rs
@@ -11,7 +11,6 @@
 extern crate uucore;
 
 use std::{
-    convert::TryInto,
     fs::File,
     io::{stdin, stdout, BufReader, Read, Stdout, Write},
     path::Path,
@@ -32,6 +31,8 @@ use crossterm::{
 use unicode_segmentation::UnicodeSegmentation;
 use unicode_width::UnicodeWidthStr;
 
+const BELL: &str = "\x07";
+
 pub mod options {
     pub const SILENT: &str = "silent";
     pub const LOGICAL: &str = "logical";
@@ -53,14 +54,14 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
     let matches = App::new(executable!())
         .about("A file perusal filter for CRT viewing.")
         .version(crate_version!())
-        // The commented arguments below are unimplemented:
-        /*
         .arg(
             Arg::with_name(options::SILENT)
                 .short("d")
                 .long(options::SILENT)
                 .help("Display help instead of ringing bell"),
         )
+        // The commented arguments below are unimplemented:
+        /*
         .arg(
             Arg::with_name(options::LOGICAL)
                 .short("f")
@@ -140,6 +141,7 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
         .get_matches_from(args);
 
     let mut buff = String::new();
+    let silent = matches.is_present(options::SILENT);
     if let Some(files) = matches.values_of(options::FILES) {
         let mut stdout = setup_term();
         let length = files.len();
@@ -162,14 +164,14 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
             }
             let mut reader = BufReader::new(File::open(file).unwrap());
             reader.read_to_string(&mut buff).unwrap();
-            more(&buff, &mut stdout, next_file.copied());
+            more(&buff, &mut stdout, next_file.copied(), silent);
             buff.clear();
         }
         reset_term(&mut stdout);
     } else if atty::isnt(atty::Stream::Stdin) {
         stdin().read_to_string(&mut buff).unwrap();
         let mut stdout = setup_term();
-        more(&buff, &mut stdout, None);
+        more(&buff, &mut stdout, None, silent);
         reset_term(&mut stdout);
     } else {
         show_usage_error!("bad usage");
@@ -204,38 +206,18 @@ fn reset_term(stdout: &mut std::io::Stdout) {
 #[inline(always)]
 fn reset_term(_: &mut usize) {}
 
-fn more(buff: &str, mut stdout: &mut Stdout, next_file: Option<&str>) {
+fn more(buff: &str, mut stdout: &mut Stdout, next_file: Option<&str>, silent: bool) {
     let (cols, rows) = terminal::size().unwrap();
     let lines = break_buff(buff, usize::from(cols));
-    let line_count: u16 = lines.len().try_into().unwrap();
 
-    let mut upper_mark = 0;
-    let mut lines_left = line_count.saturating_sub(upper_mark + rows);
-
-    draw(
-        &mut upper_mark,
-        rows,
-        &mut stdout,
-        lines.clone(),
-        line_count,
-        next_file,
-    );
-
-    let is_last = next_file.is_none();
-
-    // Specifies whether we have reached the end of the file and should
-    // return on the next key press. However, we immediately return when
-    // this is the last file.
-    let mut to_be_done = false;
-    if lines_left == 0 && is_last {
-        if is_last {
-            return;
-        } else {
-            to_be_done = true;
-        }
+    let mut pager = Pager::new(rows as usize, lines, next_file, silent);
+    pager.draw(stdout, false);
+    if pager.should_close() {
+        return;
     }
 
     loop {
+        let mut wrong_key = false;
         if event::poll(Duration::from_millis(10)).unwrap() {
             match event::read().unwrap() {
                 Event::Key(KeyEvent {
@@ -257,59 +239,127 @@ fn more(buff: &str, mut stdout: &mut Stdout, next_file: Option<&str>) {
                     code: KeyCode::Char(' '),
                     modifiers: KeyModifiers::NONE,
                 }) => {
-                    upper_mark = upper_mark.saturating_add(rows.saturating_sub(1));
+                    pager.page_down();
                 }
                 Event::Key(KeyEvent {
                     code: KeyCode::Up,
                     modifiers: KeyModifiers::NONE,
                 }) => {
-                    upper_mark = upper_mark.saturating_sub(rows.saturating_sub(1));
+                    pager.page_up();
+                }
+                _ => {
+                    wrong_key = true;
                 }
-                _ => continue,
             }
-            lines_left = line_count.saturating_sub(upper_mark + rows);
-            draw(
-                &mut upper_mark,
-                rows,
-                &mut stdout,
-                lines.clone(),
-                line_count,
-                next_file,
-            );
 
-            if lines_left == 0 {
-                if to_be_done || is_last {
-                    return;
-                }
-                to_be_done = true;
+            pager.draw(stdout, wrong_key);
+            if pager.should_close() {
+                return;
             }
         }
     }
 }
 
-fn draw(
-    upper_mark: &mut u16,
-    rows: u16,
-    mut stdout: &mut std::io::Stdout,
+struct Pager<'a> {
+    // The current line at the top of the screen
+    upper_mark: usize,
+    // The number of rows that fit on the screen
+    content_rows: usize,
     lines: Vec<String>,
-    lc: u16,
-    next_file: Option<&str>,
-) {
-    execute!(stdout, terminal::Clear(terminal::ClearType::CurrentLine)).unwrap();
-    let (up_mark, lower_mark) = calc_range(*upper_mark, rows, lc);
-    // Reduce the row by 1 for the prompt
-    let displayed_lines = lines
-        .iter()
-        .skip(up_mark.into())
-        .take(usize::from(rows.saturating_sub(1)));
+    next_file: Option<&'a str>,
+    line_count: usize,
+    close_on_down: bool,
+    silent: bool,
+}
 
-    for line in displayed_lines {
-        stdout
-            .write_all(format!("\r{}\n", line).as_bytes())
-            .unwrap();
+impl<'a> Pager<'a> {
+    fn new(rows: usize, lines: Vec<String>, next_file: Option<&'a str>, silent: bool) -> Self {
+        let line_count = lines.len();
+        Self {
+            upper_mark: 0,
+            content_rows: rows - 1,
+            lines,
+            next_file,
+            line_count,
+            close_on_down: false,
+            silent,
+        }
+    }
+
+    fn should_close(&mut self) -> bool {
+        if self.upper_mark + self.content_rows >= self.line_count {
+            if self.close_on_down {
+                return true;
+            }
+            if self.next_file.is_none() {
+                return true;
+            } else {
+                self.close_on_down = true;
+            }
+        } else {
+            self.close_on_down = false;
+        }
+        false
+    }
+
+    fn page_down(&mut self) {
+        self.upper_mark += self.content_rows;
+    }
+
+    fn page_up(&mut self) {
+        self.upper_mark = self.upper_mark.saturating_sub(self.content_rows);
+    }
+
+    fn draw(&self, stdout: &mut std::io::Stdout, wrong_key: bool) {
+        let lower_mark = self.line_count.min(self.upper_mark + self.content_rows);
+        self.draw_lines(stdout);
+        self.draw_prompt(stdout, lower_mark, wrong_key);
+        stdout.flush().unwrap();
+    }
+
+    fn draw_lines(&self, stdout: &mut std::io::Stdout) {
+        execute!(stdout, terminal::Clear(terminal::ClearType::CurrentLine)).unwrap();
+        let displayed_lines = self
+            .lines
+            .iter()
+            .skip(self.upper_mark)
+            .take(self.content_rows);
+
+        for line in displayed_lines {
+            stdout
+                .write_all(format!("\r{}\n", line).as_bytes())
+                .unwrap();
+        }
+    }
+
+    fn draw_prompt(&self, stdout: &mut Stdout, lower_mark: usize, wrong_key: bool) {
+        let status_inner = if lower_mark == self.line_count {
+            format!("Next file: {}", self.next_file.unwrap_or_default())
+        } else {
+            format!(
+                "{}%",
+                (lower_mark as f64 / self.line_count as f64 * 100.0).round() as u16
+            )
+        };
+
+        let status = format!("--More--({})", status_inner);
+
+        let banner = match (self.silent, wrong_key) {
+            (true, true) => "[Press 'h' for instructions. (unimplemented)]".to_string(),
+            (true, false) => format!("{}[Press space to continue, 'q' to quit.]", status),
+            (false, true) => format!("{}{}", status, BELL),
+            (false, false) => status,
+        };
+
+        write!(
+            stdout,
+            "\r{}{}{}",
+            Attribute::Reverse,
+            banner,
+            Attribute::Reset
+        )
+        .unwrap();
     }
-    make_prompt_and_flush(&mut stdout, lower_mark, lc, next_file);
-    *upper_mark = up_mark;
 }
 
 // Break the lines on the cols of the terminal
@@ -350,52 +400,11 @@ fn break_line(line: &str, cols: usize) -> Vec<String> {
     lines
 }
 
-// Calculate upper_mark based on certain parameters
-fn calc_range(mut upper_mark: u16, rows: u16, line_count: u16) -> (u16, u16) {
-    let mut lower_mark = upper_mark.saturating_add(rows);
-
-    if lower_mark >= line_count {
-        upper_mark = line_count.saturating_sub(rows).saturating_add(1);
-        lower_mark = line_count;
-    } else {
-        lower_mark = lower_mark.saturating_sub(1)
-    }
-    (upper_mark, lower_mark)
-}
-
-// Make a prompt similar to original more
-fn make_prompt_and_flush(stdout: &mut Stdout, lower_mark: u16, lc: u16, next_file: Option<&str>) {
-    let status = if lower_mark == lc {
-        format!("Next file: {}", next_file.unwrap_or_default())
-    } else {
-        format!(
-            "{}%",
-            (lower_mark as f64 / lc as f64 * 100.0).round() as u16
-        )
-    };
-    write!(
-        stdout,
-        "\r{}--More--({}){}",
-        Attribute::Reverse,
-        status,
-        Attribute::Reset
-    )
-    .unwrap();
-    stdout.flush().unwrap();
-}
-
 #[cfg(test)]
 mod tests {
-    use super::{break_line, calc_range};
+    use super::break_line;
     use unicode_width::UnicodeWidthStr;
 
-    // It is good to test the above functions
-    #[test]
-    fn test_calc_range() {
-        assert_eq!((0, 24), calc_range(0, 25, 100));
-        assert_eq!((50, 74), calc_range(50, 25, 100));
-        assert_eq!((76, 100), calc_range(85, 25, 100));
-    }
     #[test]
     fn test_break_lines_long() {
         let mut test_string = String::with_capacity(100);
diff --git a/src/uu/mv/src/mv.rs b/src/uu/mv/src/mv.rs
index 6b6482702..bb402737e 100644
--- a/src/uu/mv/src/mv.rs
+++ b/src/uu/mv/src/mv.rs
@@ -389,7 +389,7 @@ fn rename_with_fallback(from: &Path, to: &Path) -> io::Result<()> {
         let file_type = metadata.file_type();
 
         if file_type.is_symlink() {
-            rename_symlink_fallback(&from, &to)?;
+            rename_symlink_fallback(from, to)?;
         } else if file_type.is_dir() {
             // We remove the destination directory if it exists to match the
             // behavior of `fs::rename`. As far as I can tell, `fs_extra`'s
diff --git a/src/uu/nl/src/nl.rs b/src/uu/nl/src/nl.rs
index c062eedd9..a3181e11f 100644
--- a/src/uu/nl/src/nl.rs
+++ b/src/uu/nl/src/nl.rs
@@ -247,7 +247,7 @@ fn nl<T: Read>(reader: &mut BufReader<T>, settings: &Settings) {
     let mut line_filter: fn(&str, &regex::Regex) -> bool = pass_regex;
     for mut l in reader.lines().map(|r| r.unwrap()) {
         // Sanitize the string. We want to print the newline ourselves.
-        if !l.is_empty() && l.chars().rev().next().unwrap() == '\n' {
+        if l.ends_with('\n') {
             l.pop();
         }
         // Next we iterate through the individual chars to see if this
diff --git a/src/uu/nohup/Cargo.toml b/src/uu/nohup/Cargo.toml
index 5bbbd9dff..839219a84 100644
--- a/src/uu/nohup/Cargo.toml
+++ b/src/uu/nohup/Cargo.toml
@@ -17,6 +17,7 @@ path = "src/nohup.rs"
 [dependencies]
 clap = "2.33"
 libc = "0.2.42"
+atty = "0.2"
 uucore = { version=">=0.0.8", package="uucore", path="../../uucore", features=["fs"] }
 uucore_procs = { version=">=0.0.5", package="uucore_procs", path="../../uucore_procs" }
 
diff --git a/src/uu/nohup/src/nohup.rs b/src/uu/nohup/src/nohup.rs
index ea379ff49..4e6fd7a7e 100644
--- a/src/uu/nohup/src/nohup.rs
+++ b/src/uu/nohup/src/nohup.rs
@@ -19,7 +19,6 @@ use std::fs::{File, OpenOptions};
 use std::io::Error;
 use std::os::unix::prelude::*;
 use std::path::{Path, PathBuf};
-use uucore::fs::{is_stderr_interactive, is_stdin_interactive, is_stdout_interactive};
 use uucore::InvalidEncodingHandling;
 
 static ABOUT: &str = "Run COMMAND ignoring hangup signals.";
@@ -84,7 +83,7 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
 }
 
 fn replace_fds() {
-    if is_stdin_interactive() {
+    if atty::is(atty::Stream::Stdin) {
         let new_stdin = match File::open(Path::new("/dev/null")) {
             Ok(t) => t,
             Err(e) => crash!(2, "Cannot replace STDIN: {}", e),
@@ -94,7 +93,7 @@ fn replace_fds() {
         }
     }
 
-    if is_stdout_interactive() {
+    if atty::is(atty::Stream::Stdout) {
         let new_stdout = find_stdout();
         let fd = new_stdout.as_raw_fd();
 
@@ -103,7 +102,7 @@ fn replace_fds() {
         }
     }
 
-    if is_stderr_interactive() && unsafe { dup2(1, 2) } != 2 {
+    if atty::is(atty::Stream::Stderr) && unsafe { dup2(1, 2) } != 2 {
         crash!(2, "Cannot replace STDERR: {}", Error::last_os_error())
     }
 }
diff --git a/src/uu/numfmt/src/format.rs b/src/uu/numfmt/src/format.rs
index ebe380569..ee692d8f0 100644
--- a/src/uu/numfmt/src/format.rs
+++ b/src/uu/numfmt/src/format.rs
@@ -238,7 +238,7 @@ fn format_and_print_delimited(s: &str, options: &NumfmtOptions) -> Result<()> {
         }
 
         if field_selected {
-            print!("{}", format_string(&field.trim_start(), options, None)?);
+            print!("{}", format_string(field.trim_start(), options, None)?);
         } else {
             // print unselected field without conversion
             print!("{}", field);
@@ -271,7 +271,7 @@ fn format_and_print_whitespace(s: &str, options: &NumfmtOptions) -> Result<()> {
                 None
             };
 
-            print!("{}", format_string(&field, options, implicit_padding)?);
+            print!("{}", format_string(field, options, implicit_padding)?);
         } else {
             // print unselected field without conversion
             print!("{}{}", prefix, field);
diff --git a/src/uu/od/src/formatteriteminfo.rs b/src/uu/od/src/formatteriteminfo.rs
index d44d97a92..13cf62246 100644
--- a/src/uu/od/src/formatteriteminfo.rs
+++ b/src/uu/od/src/formatteriteminfo.rs
@@ -2,6 +2,7 @@
 
 use std::fmt;
 
+#[allow(clippy::enum_variant_names)]
 #[derive(Copy)]
 pub enum FormatWriter {
     IntWriter(fn(u64) -> String),
diff --git a/src/uu/od/src/inputdecoder.rs b/src/uu/od/src/inputdecoder.rs
index f6ba59885..606495461 100644
--- a/src/uu/od/src/inputdecoder.rs
+++ b/src/uu/od/src/inputdecoder.rs
@@ -115,7 +115,7 @@ impl<'a> MemoryDecoder<'a> {
 
     /// Creates a clone of the internal buffer. The clone only contain the valid data.
     pub fn clone_buffer(&self, other: &mut Vec<u8>) {
-        other.clone_from(&self.data);
+        other.clone_from(self.data);
         other.resize(self.used_normal_length, 0);
     }
 
diff --git a/src/uu/od/src/od.rs b/src/uu/od/src/od.rs
index 33303f0fc..bf6c39011 100644
--- a/src/uu/od/src/od.rs
+++ b/src/uu/od/src/od.rs
@@ -43,6 +43,7 @@ use crate::partialreader::*;
 use crate::peekreader::*;
 use crate::prn_char::format_ascii_dump;
 use clap::{self, crate_version, AppSettings, Arg, ArgMatches};
+use uucore::parse_size::ParseSizeError;
 use uucore::InvalidEncodingHandling;
 
 const PEEK_BUFFER_SIZE: usize = 4; // utf-8 can be 4 bytes
@@ -128,42 +129,34 @@ impl OdOptions {
             }
         };
 
-        let mut skip_bytes = match matches.value_of(options::SKIP_BYTES) {
-            None => 0,
-            Some(s) => match parse_number_of_bytes(&s) {
-                Ok(i) => i,
-                Err(_) => {
-                    return Err(format!("Invalid argument --skip-bytes={}", s));
-                }
-            },
-        };
+        let mut skip_bytes = matches.value_of(options::SKIP_BYTES).map_or(0, |s| {
+            parse_number_of_bytes(s).unwrap_or_else(|e| {
+                crash!(1, "{}", format_error_message(e, s, options::SKIP_BYTES))
+            })
+        });
 
         let mut label: Option<usize> = None;
 
-        let input_strings = match parse_inputs(&matches) {
-            Ok(CommandLineInputs::FileNames(v)) => v,
-            Ok(CommandLineInputs::FileAndOffset((f, s, l))) => {
+        let parsed_input = parse_inputs(&matches).map_err(|e| format!("Invalid inputs: {}", e))?;
+        let input_strings = match parsed_input {
+            CommandLineInputs::FileNames(v) => v,
+            CommandLineInputs::FileAndOffset((f, s, l)) => {
                 skip_bytes = s;
                 label = l;
                 vec![f]
             }
-            Err(e) => {
-                return Err(format!("Invalid inputs: {}", e));
-            }
         };
 
-        let formats = match parse_format_flags(&args) {
-            Ok(f) => f,
-            Err(e) => {
-                return Err(e);
-            }
-        };
+        let formats = parse_format_flags(&args)?;
+
+        let mut line_bytes = matches.value_of(options::WIDTH).map_or(16, |s| {
+            if matches.occurrences_of(options::WIDTH) == 0 {
+                return 16;
+            };
+            parse_number_of_bytes(s)
+                .unwrap_or_else(|e| crash!(1, "{}", format_error_message(e, s, options::WIDTH)))
+        });
 
-        let mut line_bytes = match matches.value_of(options::WIDTH) {
-            None => 16,
-            Some(_) if matches.occurrences_of(options::WIDTH) == 0 => 16,
-            Some(s) => s.parse::<usize>().unwrap_or(0),
-        };
         let min_bytes = formats.iter().fold(1, |max, next| {
             cmp::max(max, next.formatter_item_info.byte_size)
         });
@@ -174,15 +167,11 @@ impl OdOptions {
 
         let output_duplicates = matches.is_present(options::OUTPUT_DUPLICATES);
 
-        let read_bytes = match matches.value_of(options::READ_BYTES) {
-            None => None,
-            Some(s) => match parse_number_of_bytes(&s) {
-                Ok(i) => Some(i),
-                Err(_) => {
-                    return Err(format!("Invalid argument --read-bytes={}", s));
-                }
-            },
-        };
+        let read_bytes = matches.value_of(options::READ_BYTES).map(|s| {
+            parse_number_of_bytes(s).unwrap_or_else(|e| {
+                crash!(1, "{}", format_error_message(e, s, options::READ_BYTES))
+            })
+        });
 
         let radix = match matches.value_of(options::ADDRESS_RADIX) {
             None => Radix::Octal,
@@ -263,7 +252,7 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
                 .short("S")
                 .long(options::STRINGS)
                 .help(
-                    "output strings of at least BYTES graphic chars. 3 is assumed when \
+                    "NotImplemented: output strings of at least BYTES graphic chars. 3 is assumed when \
                      BYTES is not specified.",
                 )
                 .default_value("3")
@@ -453,8 +442,7 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
 
     let od_options = match OdOptions::new(clap_matches, args) {
         Err(s) => {
-            show_usage_error!("{}", s);
-            return 1;
+            crash!(1, "{}", s);
         }
         Ok(o) => o,
     };
@@ -537,7 +525,7 @@ where
                     print_bytes(
                         &input_offset.format_byte_offset(),
                         &memory_decoder,
-                        &output_info,
+                        output_info,
                     );
                 }
 
@@ -636,3 +624,13 @@ fn open_input_peek_reader(
     let pr = PartialReader::new(mf, skip_bytes, read_bytes);
     PeekReader::new(pr)
 }
+
+fn format_error_message(error: ParseSizeError, s: &str, option: &str) -> String {
+    // NOTE:
+    // GNU's od echos affected flag, -N or --read-bytes (-j or --skip-bytes, etc.), depending user's selection
+    // GNU's od does distinguish between "invalid (suffix in) argument"
+    match error {
+        ParseSizeError::ParseFailure(_) => format!("invalid --{} argument '{}'", option, s),
+        ParseSizeError::SizeTooBig(_) => format!("--{} argument '{}' too large", option, s),
+    }
+}
diff --git a/src/uu/od/src/output_info.rs b/src/uu/od/src/output_info.rs
index a204fa36e..49c2a09a2 100644
--- a/src/uu/od/src/output_info.rs
+++ b/src/uu/od/src/output_info.rs
@@ -68,7 +68,7 @@ impl OutputInfo {
         let print_width_line = print_width_block * (line_bytes / byte_size_block);
 
         let spaced_formatters =
-            OutputInfo::create_spaced_formatter_info(&formats, byte_size_block, print_width_block);
+            OutputInfo::create_spaced_formatter_info(formats, byte_size_block, print_width_block);
 
         OutputInfo {
             byte_size_line: line_bytes,
diff --git a/src/uu/od/src/parse_formats.rs b/src/uu/od/src/parse_formats.rs
index abf05ea18..f5b150d61 100644
--- a/src/uu/od/src/parse_formats.rs
+++ b/src/uu/od/src/parse_formats.rs
@@ -108,10 +108,8 @@ pub fn parse_format_flags(args: &[String]) -> Result<Vec<ParsedFormatterItemInfo
 
     for arg in arg_iter {
         if expect_type_string {
-            match parse_type_string(arg) {
-                Ok(v) => formats.extend(v.into_iter()),
-                Err(e) => return Err(e),
-            }
+            let v = parse_type_string(arg)?;
+            formats.extend(v.into_iter());
             expect_type_string = false;
         } else if arg.starts_with("--") {
             if arg.len() == 2 {
@@ -119,10 +117,8 @@ pub fn parse_format_flags(args: &[String]) -> Result<Vec<ParsedFormatterItemInfo
             }
             if arg.starts_with("--format=") {
                 let params: String = arg.chars().skip_while(|c| *c != '=').skip(1).collect();
-                match parse_type_string(&params) {
-                    Ok(v) => formats.extend(v.into_iter()),
-                    Err(e) => return Err(e),
-                }
+                let v = parse_type_string(&params)?;
+                formats.extend(v.into_iter());
             }
             if arg == "--format" {
                 expect_type_string = true;
@@ -145,10 +141,8 @@ pub fn parse_format_flags(args: &[String]) -> Result<Vec<ParsedFormatterItemInfo
                 }
             }
             if !format_spec.is_empty() {
-                match parse_type_string(&format_spec) {
-                    Ok(v) => formats.extend(v.into_iter()),
-                    Err(e) => return Err(e),
-                }
+                let v = parse_type_string(&format_spec)?;
+                formats.extend(v.into_iter());
                 expect_type_string = false;
             }
         }
@@ -275,17 +269,13 @@ fn parse_type_string(params: &str) -> Result<Vec<ParsedFormatterItemInfo>, Strin
     let mut chars = params.chars();
     let mut ch = chars.next();
 
-    while ch.is_some() {
-        let type_char = ch.unwrap();
-        let type_char = match format_type(type_char) {
-            Some(t) => t,
-            None => {
-                return Err(format!(
-                    "unexpected char '{}' in format specification '{}'",
-                    type_char, params
-                ));
-            }
-        };
+    while let Some(type_char) = ch {
+        let type_char = format_type(type_char).ok_or_else(|| {
+            format!(
+                "unexpected char '{}' in format specification '{}'",
+                type_char, params
+            )
+        })?;
 
         let type_cat = format_type_category(type_char);
 
@@ -301,30 +291,25 @@ fn parse_type_string(params: &str) -> Result<Vec<ParsedFormatterItemInfo>, Strin
                 ch = chars.next();
             }
             if !decimal_size.is_empty() {
-                byte_size = match decimal_size.parse() {
-                    Err(_) => {
-                        return Err(format!(
-                            "invalid number '{}' in format specification '{}'",
-                            decimal_size, params
-                        ))
-                    }
-                    Ok(n) => n,
-                }
+                byte_size = decimal_size.parse().map_err(|_| {
+                    format!(
+                        "invalid number '{}' in format specification '{}'",
+                        decimal_size, params
+                    )
+                })?;
             }
         }
         if is_format_dump_char(ch, &mut show_ascii_dump) {
             ch = chars.next();
         }
 
-        match od_format_type(type_char, byte_size) {
-            Some(ft) => formats.push(ParsedFormatterItemInfo::new(ft, show_ascii_dump)),
-            None => {
-                return Err(format!(
-                    "invalid size '{}' in format specification '{}'",
-                    byte_size, params
-                ))
-            }
-        }
+        let ft = od_format_type(type_char, byte_size).ok_or_else(|| {
+            format!(
+                "invalid size '{}' in format specification '{}'",
+                byte_size, params
+            )
+        })?;
+        formats.push(ParsedFormatterItemInfo::new(ft, show_ascii_dump));
     }
 
     Ok(formats)
@@ -335,16 +320,13 @@ pub fn parse_format_flags_str(
     args_str: &Vec<&'static str>,
 ) -> Result<Vec<FormatterItemInfo>, String> {
     let args: Vec<String> = args_str.iter().map(|s| s.to_string()).collect();
-    match parse_format_flags(&args) {
-        Err(e) => Err(e),
-        Ok(v) => {
-            // tests using this function assume add_ascii_dump is not set
-            Ok(v.into_iter()
-                .inspect(|f| assert!(!f.add_ascii_dump))
-                .map(|f| f.formatter_item_info)
-                .collect())
-        }
-    }
+    parse_format_flags(&args).map(|v| {
+        // tests using this function assume add_ascii_dump is not set
+        v.into_iter()
+            .inspect(|f| assert!(!f.add_ascii_dump))
+            .map(|f| f.formatter_item_info)
+            .collect()
+    })
 }
 
 #[test]
diff --git a/src/uu/od/src/parse_inputs.rs b/src/uu/od/src/parse_inputs.rs
index 288c0870f..419b7173d 100644
--- a/src/uu/od/src/parse_inputs.rs
+++ b/src/uu/od/src/parse_inputs.rs
@@ -55,7 +55,7 @@ pub fn parse_inputs(matches: &dyn CommandLineOpts) -> Result<CommandLineInputs,
         // if any of the options -A, -j, -N, -t, -v or -w are present there is no offset
         if !matches.opts_present(&["A", "j", "N", "t", "v", "w"]) {
             // test if the last input can be parsed as an offset.
-            let offset = parse_offset_operand(&input_strings[input_strings.len() - 1]);
+            let offset = parse_offset_operand(input_strings[input_strings.len() - 1]);
             if let Ok(n) = offset {
                 // if there is just 1 input (stdin), an offset must start with '+'
                 if input_strings.len() == 1 && input_strings[0].starts_with('+') {
@@ -88,7 +88,7 @@ pub fn parse_inputs_traditional(input_strings: Vec<&str>) -> Result<CommandLineI
     match input_strings.len() {
         0 => Ok(CommandLineInputs::FileNames(vec!["-".to_string()])),
         1 => {
-            let offset0 = parse_offset_operand(&input_strings[0]);
+            let offset0 = parse_offset_operand(input_strings[0]);
             Ok(match offset0 {
                 Ok(n) => CommandLineInputs::FileAndOffset(("-".to_string(), n, None)),
                 _ => CommandLineInputs::FileNames(
@@ -97,8 +97,8 @@ pub fn parse_inputs_traditional(input_strings: Vec<&str>) -> Result<CommandLineI
             })
         }
         2 => {
-            let offset0 = parse_offset_operand(&input_strings[0]);
-            let offset1 = parse_offset_operand(&input_strings[1]);
+            let offset0 = parse_offset_operand(input_strings[0]);
+            let offset1 = parse_offset_operand(input_strings[1]);
             match (offset0, offset1) {
                 (Ok(n), Ok(m)) => Ok(CommandLineInputs::FileAndOffset((
                     "-".to_string(),
@@ -114,8 +114,8 @@ pub fn parse_inputs_traditional(input_strings: Vec<&str>) -> Result<CommandLineI
             }
         }
         3 => {
-            let offset = parse_offset_operand(&input_strings[1]);
-            let label = parse_offset_operand(&input_strings[2]);
+            let offset = parse_offset_operand(input_strings[1]);
+            let label = parse_offset_operand(input_strings[2]);
             match (offset, label) {
                 (Ok(n), Ok(m)) => Ok(CommandLineInputs::FileAndOffset((
                     input_strings[0].to_string(),
diff --git a/src/uu/od/src/parse_nrofbytes.rs b/src/uu/od/src/parse_nrofbytes.rs
index d2ba1527b..d6329c60a 100644
--- a/src/uu/od/src/parse_nrofbytes.rs
+++ b/src/uu/od/src/parse_nrofbytes.rs
@@ -1,14 +1,17 @@
-pub fn parse_number_of_bytes(s: &str) -> Result<usize, &'static str> {
+use uucore::parse_size::{parse_size, ParseSizeError};
+
+pub fn parse_number_of_bytes(s: &str) -> Result<usize, ParseSizeError> {
     let mut start = 0;
     let mut len = s.len();
-    let mut radix = 10;
+    let mut radix = 16;
     let mut multiply = 1;
 
     if s.starts_with("0x") || s.starts_with("0X") {
         start = 2;
-        radix = 16;
     } else if s.starts_with('0') {
         radix = 8;
+    } else {
+        return parse_size(&s[start..]);
     }
 
     let mut ends_with = s.chars().rev();
@@ -56,78 +59,33 @@ pub fn parse_number_of_bytes(s: &str) -> Result<usize, &'static str> {
                 Some('P') => 1000 * 1000 * 1000 * 1000 * 1000,
                 #[cfg(target_pointer_width = "64")]
                 Some('E') => 1000 * 1000 * 1000 * 1000 * 1000 * 1000,
-                _ => return Err("parse failed"),
+                _ => return Err(ParseSizeError::ParseFailure(s.to_string())),
             }
         }
         _ => {}
     }
 
-    match usize::from_str_radix(&s[start..len], radix) {
-        Ok(i) => Ok(i * multiply),
-        Err(_) => Err("parse failed"),
-    }
-}
-
-#[allow(dead_code)]
-fn parse_number_of_bytes_str(s: &str) -> Result<usize, &'static str> {
-    parse_number_of_bytes(&String::from(s))
+    let factor = match usize::from_str_radix(&s[start..len], radix) {
+        Ok(f) => f,
+        Err(e) => return Err(ParseSizeError::ParseFailure(e.to_string())),
+    };
+    factor
+        .checked_mul(multiply)
+        .ok_or_else(|| ParseSizeError::SizeTooBig(s.to_string()))
 }
 
 #[test]
 fn test_parse_number_of_bytes() {
-    // normal decimal numbers
-    assert_eq!(0, parse_number_of_bytes_str("0").unwrap());
-    assert_eq!(5, parse_number_of_bytes_str("5").unwrap());
-    assert_eq!(999, parse_number_of_bytes_str("999").unwrap());
-    assert_eq!(2 * 512, parse_number_of_bytes_str("2b").unwrap());
-    assert_eq!(2 * 1024, parse_number_of_bytes_str("2k").unwrap());
-    assert_eq!(4 * 1024, parse_number_of_bytes_str("4K").unwrap());
-    assert_eq!(2 * 1048576, parse_number_of_bytes_str("2m").unwrap());
-    assert_eq!(4 * 1048576, parse_number_of_bytes_str("4M").unwrap());
-    assert_eq!(1073741824, parse_number_of_bytes_str("1G").unwrap());
-    assert_eq!(2000, parse_number_of_bytes_str("2kB").unwrap());
-    assert_eq!(4000, parse_number_of_bytes_str("4KB").unwrap());
-    assert_eq!(2000000, parse_number_of_bytes_str("2mB").unwrap());
-    assert_eq!(4000000, parse_number_of_bytes_str("4MB").unwrap());
-    assert_eq!(2000000000, parse_number_of_bytes_str("2GB").unwrap());
-
     // octal input
-    assert_eq!(8, parse_number_of_bytes_str("010").unwrap());
-    assert_eq!(8 * 512, parse_number_of_bytes_str("010b").unwrap());
-    assert_eq!(8 * 1024, parse_number_of_bytes_str("010k").unwrap());
-    assert_eq!(8 * 1048576, parse_number_of_bytes_str("010m").unwrap());
+    assert_eq!(8, parse_number_of_bytes("010").unwrap());
+    assert_eq!(8 * 512, parse_number_of_bytes("010b").unwrap());
+    assert_eq!(8 * 1024, parse_number_of_bytes("010k").unwrap());
+    assert_eq!(8 * 1_048_576, parse_number_of_bytes("010m").unwrap());
 
     // hex input
-    assert_eq!(15, parse_number_of_bytes_str("0xf").unwrap());
-    assert_eq!(15, parse_number_of_bytes_str("0XF").unwrap());
-    assert_eq!(27, parse_number_of_bytes_str("0x1b").unwrap());
-    assert_eq!(16 * 1024, parse_number_of_bytes_str("0x10k").unwrap());
-    assert_eq!(16 * 1048576, parse_number_of_bytes_str("0x10m").unwrap());
-
-    // invalid input
-    parse_number_of_bytes_str("").unwrap_err();
-    parse_number_of_bytes_str("-1").unwrap_err();
-    parse_number_of_bytes_str("1e2").unwrap_err();
-    parse_number_of_bytes_str("xyz").unwrap_err();
-    parse_number_of_bytes_str("b").unwrap_err();
-    parse_number_of_bytes_str("1Y").unwrap_err();
-    parse_number_of_bytes_str("∞").unwrap_err();
-}
-
-#[test]
-#[cfg(target_pointer_width = "64")]
-fn test_parse_number_of_bytes_64bits() {
-    assert_eq!(1099511627776, parse_number_of_bytes_str("1T").unwrap());
-    assert_eq!(1125899906842624, parse_number_of_bytes_str("1P").unwrap());
-    assert_eq!(
-        1152921504606846976,
-        parse_number_of_bytes_str("1E").unwrap()
-    );
-
-    assert_eq!(2000000000000, parse_number_of_bytes_str("2TB").unwrap());
-    assert_eq!(2000000000000000, parse_number_of_bytes_str("2PB").unwrap());
-    assert_eq!(
-        2000000000000000000,
-        parse_number_of_bytes_str("2EB").unwrap()
-    );
+    assert_eq!(15, parse_number_of_bytes("0xf").unwrap());
+    assert_eq!(15, parse_number_of_bytes("0XF").unwrap());
+    assert_eq!(27, parse_number_of_bytes("0x1b").unwrap());
+    assert_eq!(16 * 1024, parse_number_of_bytes("0x10k").unwrap());
+    assert_eq!(16 * 1_048_576, parse_number_of_bytes("0x10m").unwrap());
 }
diff --git a/src/uu/od/src/partialreader.rs b/src/uu/od/src/partialreader.rs
index ee3588830..f155a7bd2 100644
--- a/src/uu/od/src/partialreader.rs
+++ b/src/uu/od/src/partialreader.rs
@@ -36,16 +36,15 @@ impl<R: Read> Read for PartialReader<R> {
             while self.skip > 0 {
                 let skip_count = cmp::min(self.skip, MAX_SKIP_BUFFER);
 
-                match self.inner.read(&mut bytes[..skip_count]) {
-                    Ok(0) => {
+                match self.inner.read(&mut bytes[..skip_count])? {
+                    0 => {
                         // this is an error as we still have more to skip
                         return Err(io::Error::new(
                             io::ErrorKind::UnexpectedEof,
                             "tried to skip past end of input",
                         ));
                     }
-                    Ok(n) => self.skip -= n,
-                    Err(e) => return Err(e),
+                    n => self.skip -= n,
                 }
             }
         }
diff --git a/src/uu/pathchk/src/pathchk.rs b/src/uu/pathchk/src/pathchk.rs
index 9667e0ba1..358881509 100644
--- a/src/uu/pathchk/src/pathchk.rs
+++ b/src/uu/pathchk/src/pathchk.rs
@@ -118,10 +118,10 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
 // check a path, given as a slice of it's components and an operating mode
 fn check_path(mode: &Mode, path: &[String]) -> bool {
     match *mode {
-        Mode::Basic => check_basic(&path),
-        Mode::Extra => check_default(&path) && check_extra(&path),
-        Mode::Both => check_basic(&path) && check_extra(&path),
-        _ => check_default(&path),
+        Mode::Basic => check_basic(path),
+        Mode::Extra => check_default(path) && check_extra(path),
+        Mode::Both => check_basic(path) && check_extra(path),
+        _ => check_default(path),
     }
 }
 
@@ -156,7 +156,7 @@ fn check_basic(path: &[String]) -> bool {
             );
             return false;
         }
-        if !check_portable_chars(&p) {
+        if !check_portable_chars(p) {
             return false;
         }
     }
@@ -168,7 +168,7 @@ fn check_basic(path: &[String]) -> bool {
 fn check_extra(path: &[String]) -> bool {
     // components: leading hyphens
     for p in path {
-        if !no_leading_hyphen(&p) {
+        if !no_leading_hyphen(p) {
             writeln!(
                 &mut std::io::stderr(),
                 "leading hyphen in file name component '{}'",
@@ -241,13 +241,14 @@ fn no_leading_hyphen(path_segment: &str) -> bool {
 
 // check whether a path segment contains only valid (read: portable) characters
 fn check_portable_chars(path_segment: &str) -> bool {
-    let valid_str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789._-".to_string();
-    for ch in path_segment.chars() {
-        if !valid_str.contains(ch) {
+    const VALID_CHARS: &[u8] = b"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789._-";
+    for (i, ch) in path_segment.as_bytes().iter().enumerate() {
+        if !VALID_CHARS.contains(ch) {
+            let invalid = path_segment[i..].chars().next().unwrap();
             writeln!(
                 &mut std::io::stderr(),
                 "nonportable character '{}' in file name component '{}'",
-                ch,
+                invalid,
                 path_segment
             );
             return false;
diff --git a/src/uu/pinky/src/pinky.rs b/src/uu/pinky/src/pinky.rs
index 27dcc2421..d15730b32 100644
--- a/src/uu/pinky/src/pinky.rs
+++ b/src/uu/pinky/src/pinky.rs
@@ -283,7 +283,7 @@ impl Pinky {
             }
         }
 
-        print!(" {}", time_string(&ut));
+        print!(" {}", time_string(ut));
 
         let mut s = ut.host();
         if self.include_where && !s.is_empty() {
diff --git a/src/uu/pr/src/pr.rs b/src/uu/pr/src/pr.rs
index 486cedc00..239a0970f 100644
--- a/src/uu/pr/src/pr.rs
+++ b/src/uu/pr/src/pr.rs
@@ -401,18 +401,18 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
 
     for file_group in file_groups {
         let result_options = build_options(&matches, &file_group, args.join(" "));
+        let options = match result_options {
+            Ok(options) => options,
+            Err(err) => {
+                print_error(&matches, err);
+                return 1;
+            }
+        };
 
-        if result_options.is_err() {
-            print_error(&matches, result_options.err().unwrap());
-            return 1;
-        }
-
-        let options = &result_options.unwrap();
-
-        let cmd_result = if file_group.len() == 1 {
-            pr(&file_group.get(0).unwrap(), options)
+        let cmd_result = if let Ok(group) = file_group.iter().exactly_one() {
+            pr(group, &options)
         } else {
-            mpr(&file_group, options)
+            mpr(&file_group, &options)
         };
 
         let status = match cmd_result {
@@ -442,11 +442,12 @@ fn recreate_arguments(args: &[String]) -> Vec<String> {
     let mut arguments = args.to_owned();
     let num_option = args.iter().find_position(|x| n_regex.is_match(x.trim()));
     if let Some((pos, _value)) = num_option {
-        let num_val_opt = args.get(pos + 1);
-        if num_val_opt.is_some() && !num_regex.is_match(num_val_opt.unwrap()) {
-            let could_be_file = arguments.remove(pos + 1);
-            arguments.insert(pos + 1, format!("{}", NumberingMode::default().width));
-            arguments.insert(pos + 2, could_be_file);
+        if let Some(num_val_opt) = args.get(pos + 1) {
+            if !num_regex.is_match(num_val_opt) {
+                let could_be_file = arguments.remove(pos + 1);
+                arguments.insert(pos + 1, format!("{}", NumberingMode::default().width));
+                arguments.insert(pos + 2, could_be_file);
+            }
         }
     }
 
@@ -666,12 +667,13 @@ fn build_options(
         None => end_page_in_plus_option,
     };
 
-    if end_page.is_some() && start_page > end_page.unwrap() {
-        return Err(PrError::EncounteredErrors(format!(
-            "invalid --pages argument '{}:{}'",
-            start_page,
-            end_page.unwrap()
-        )));
+    if let Some(end_page) = end_page {
+        if start_page > end_page {
+            return Err(PrError::EncounteredErrors(format!(
+                "invalid --pages argument '{}:{}'",
+                start_page, end_page
+            )));
+        }
     }
 
     let default_lines_per_page = if form_feed_used {
@@ -947,7 +949,7 @@ fn read_stream_and_create_pages(
                 let current_page = x + 1;
 
                 current_page >= start_page
-                    && (last_page.is_none() || current_page <= last_page.unwrap())
+                    && last_page.map_or(true, |last_page| current_page <= last_page)
             }),
     )
 }
@@ -996,8 +998,8 @@ fn mpr(paths: &[String], options: &OutputOptions) -> Result<i32, PrError> {
 
     for (_key, file_line_group) in file_line_groups.into_iter() {
         for file_line in file_line_group {
-            if file_line.line_content.is_err() {
-                return Err(file_line.line_content.unwrap_err().into());
+            if let Err(e) = file_line.line_content {
+                return Err(e.into());
             }
             let new_page_number = file_line.page_number;
             if page_counter != new_page_number {
@@ -1030,8 +1032,7 @@ fn print_page(lines: &[FileLine], options: &OutputOptions, page: usize) -> Resul
 
     let lines_written = write_columns(lines, options, out)?;
 
-    for index in 0..trailer_content.len() {
-        let x = trailer_content.get(index).unwrap();
+    for (index, x) in trailer_content.iter().enumerate() {
         out.write_all(x.as_bytes())?;
         if index + 1 != trailer_content.len() {
             out.write_all(line_separator)?;
@@ -1074,8 +1075,7 @@ fn write_columns(
         let mut offset = 0;
         for col in 0..columns {
             let mut inserted = 0;
-            for i in offset..lines.len() {
-                let line = lines.get(i).unwrap();
+            for line in &lines[offset..] {
                 if line.file_id != col {
                     break;
                 }
@@ -1114,7 +1114,7 @@ fn write_columns(
         for (i, cell) in row.iter().enumerate() {
             if cell.is_none() && options.merge_files_print.is_some() {
                 out.write_all(
-                    get_line_for_printing(&options, &blank_line, columns, i, &line_width, indexes)
+                    get_line_for_printing(options, &blank_line, columns, i, &line_width, indexes)
                         .as_bytes(),
                 )?;
             } else if cell.is_none() {
@@ -1124,7 +1124,7 @@ fn write_columns(
                 let file_line = cell.unwrap();
 
                 out.write_all(
-                    get_line_for_printing(&options, file_line, columns, i, &line_width, indexes)
+                    get_line_for_printing(options, file_line, columns, i, &line_width, indexes)
                         .as_bytes(),
                 )?;
                 lines_printed += 1;
@@ -1149,7 +1149,7 @@ fn get_line_for_printing(
     indexes: usize,
 ) -> String {
     let blank_line = String::new();
-    let formatted_line_number = get_formatted_line_number(&options, file_line.line_number, index);
+    let formatted_line_number = get_formatted_line_number(options, file_line.line_number, index);
 
     let mut complete_line = format!(
         "{}{}",
diff --git a/src/uu/printf/src/tokenize/num_format/formatters/cninetyninehexfloatf.rs b/src/uu/printf/src/tokenize/num_format/formatters/cninetyninehexfloatf.rs
index f96a991b5..0ca993680 100644
--- a/src/uu/printf/src/tokenize/num_format/formatters/cninetyninehexfloatf.rs
+++ b/src/uu/printf/src/tokenize/num_format/formatters/cninetyninehexfloatf.rs
@@ -26,7 +26,7 @@ impl Formatter for CninetyNineHexFloatf {
     ) -> Option<FormatPrimitive> {
         let second_field = field.second_field.unwrap_or(6) + 1;
         let analysis = FloatAnalysis::analyze(
-            &str_in,
+            str_in,
             initial_prefix,
             Some(second_field as usize),
             None,
diff --git a/src/uu/printf/src/tokenize/num_format/formatters/decf.rs b/src/uu/printf/src/tokenize/num_format/formatters/decf.rs
index 5798eadcb..3376345e0 100644
--- a/src/uu/printf/src/tokenize/num_format/formatters/decf.rs
+++ b/src/uu/printf/src/tokenize/num_format/formatters/decf.rs
@@ -55,18 +55,9 @@ impl Formatter for Decf {
         );
         // strip trailing zeroes
         if let Some(ref post_dec) = f_sci.post_decimal {
-            let mut i = post_dec.len();
-            {
-                let mut it = post_dec.chars();
-                while let Some(c) = it.next_back() {
-                    if c != '0' {
-                        break;
-                    }
-                    i -= 1;
-                }
-            }
-            if i != post_dec.len() {
-                f_sci.post_decimal = Some(String::from(&post_dec[0..i]));
+            let trimmed = post_dec.trim_end_matches('0');
+            if trimmed.len() != post_dec.len() {
+                f_sci.post_decimal = Some(trimmed.to_owned());
             }
         }
         let f_fl = get_primitive_dec(
diff --git a/src/uu/printf/src/tokenize/num_format/formatters/float_common.rs b/src/uu/printf/src/tokenize/num_format/formatters/float_common.rs
index dd8259233..97009b586 100644
--- a/src/uu/printf/src/tokenize/num_format/formatters/float_common.rs
+++ b/src/uu/printf/src/tokenize/num_format/formatters/float_common.rs
@@ -247,8 +247,12 @@ pub fn get_primitive_dec(
                 first_segment.len() as isize - 1,
             )
         } else {
-            match first_segment.chars().next() {
-                Some('0') => {
+            match first_segment
+                .chars()
+                .next()
+                .expect("float_common: no chars in first segment.")
+            {
+                '0' => {
                     let it = second_segment.chars().enumerate();
                     let mut m: isize = 0;
                     let mut pre = String::from("0");
@@ -266,10 +270,7 @@ pub fn get_primitive_dec(
                     }
                     (pre, post, m)
                 }
-                Some(_) => (first_segment, second_segment, 0),
-                None => {
-                    panic!("float_common: no chars in first segment.");
-                }
+                _ => (first_segment, second_segment, 0),
             }
         }
     } else {
@@ -298,11 +299,11 @@ pub fn get_primitive_dec(
 pub fn primitive_to_str_common(prim: &FormatPrimitive, field: &FormatField) -> String {
     let mut final_str = String::new();
     if let Some(ref prefix) = prim.prefix {
-        final_str.push_str(&prefix);
+        final_str.push_str(prefix);
     }
     match prim.pre_decimal {
         Some(ref pre_decimal) => {
-            final_str.push_str(&pre_decimal);
+            final_str.push_str(pre_decimal);
         }
         None => {
             panic!(
diff --git a/src/uu/printf/src/tokenize/num_format/formatters/floatf.rs b/src/uu/printf/src/tokenize/num_format/formatters/floatf.rs
index aed50f18e..afb2bcf08 100644
--- a/src/uu/printf/src/tokenize/num_format/formatters/floatf.rs
+++ b/src/uu/printf/src/tokenize/num_format/formatters/floatf.rs
@@ -21,7 +21,7 @@ impl Formatter for Floatf {
     ) -> Option<FormatPrimitive> {
         let second_field = field.second_field.unwrap_or(6) + 1;
         let analysis = FloatAnalysis::analyze(
-            &str_in,
+            str_in,
             initial_prefix,
             None,
             Some(second_field as usize),
diff --git a/src/uu/printf/src/tokenize/num_format/formatters/intf.rs b/src/uu/printf/src/tokenize/num_format/formatters/intf.rs
index 02c59211b..b6c18d436 100644
--- a/src/uu/printf/src/tokenize/num_format/formatters/intf.rs
+++ b/src/uu/printf/src/tokenize/num_format/formatters/intf.rs
@@ -252,7 +252,7 @@ impl Formatter for Intf {
     fn primitive_to_str(&self, prim: &FormatPrimitive, field: FormatField) -> String {
         let mut final_str: String = String::new();
         if let Some(ref prefix) = prim.prefix {
-            final_str.push_str(&prefix);
+            final_str.push_str(prefix);
         }
         // integral second fields is zero-padded minimum-width
         // which gets handled before general minimum-width
@@ -266,7 +266,7 @@ impl Formatter for Intf {
                         i -= 1;
                     }
                 }
-                final_str.push_str(&pre_decimal);
+                final_str.push_str(pre_decimal);
             }
             None => {
                 panic!(
diff --git a/src/uu/printf/src/tokenize/num_format/num_format.rs b/src/uu/printf/src/tokenize/num_format/num_format.rs
index a8a60cc57..b32731f2d 100644
--- a/src/uu/printf/src/tokenize/num_format/num_format.rs
+++ b/src/uu/printf/src/tokenize/num_format/num_format.rs
@@ -235,7 +235,7 @@ pub fn num_format(field: &FormatField, in_str_opt: Option<&String>) -> Option<St
                     let as_str = format!("{}", provided_num);
                     let initial_prefix = get_initial_prefix(
                         &as_str,
-                        &field.field_type
+                        field.field_type
                     );
                     tmp=formatter.get_primitive(field, &initial_prefix, &as_str)
                         .expect("err during default provided num");
@@ -258,7 +258,7 @@ pub fn num_format(field: &FormatField, in_str_opt: Option<&String>) -> Option<St
             // any formatter (int or float)
             let initial_prefix = get_initial_prefix(
                 in_str,
-                &field.field_type
+                field.field_type
             );
             // then get the FormatPrimitive from the Formatter
             formatter.get_primitive(field, &initial_prefix, in_str)
diff --git a/src/uu/printf/src/tokenize/sub.rs b/src/uu/printf/src/tokenize/sub.rs
index 249003f85..d01e00699 100644
--- a/src/uu/printf/src/tokenize/sub.rs
+++ b/src/uu/printf/src/tokenize/sub.rs
@@ -275,7 +275,7 @@ impl SubParser {
                 }
                 None => {
                     text_so_far.push('%');
-                    err_conv(&text_so_far);
+                    err_conv(text_so_far);
                     false
                 }
             }
diff --git a/src/uu/ptx/src/ptx.rs b/src/uu/ptx/src/ptx.rs
index 69960ac49..31da8f05d 100644
--- a/src/uu/ptx/src/ptx.rs
+++ b/src/uu/ptx/src/ptx.rs
@@ -213,7 +213,7 @@ fn read_input(input_files: &[String], config: &Config) -> FileMap {
         files.push("-");
     } else if config.gnu_ext {
         for file in input_files {
-            files.push(&file);
+            files.push(file);
         }
     } else {
         files.push(&input_files[0]);
@@ -503,7 +503,7 @@ fn format_tex_line(
     let keyword = &line[word_ref.position..word_ref.position_end];
     let after_chars_trim_idx = (word_ref.position_end, chars_line.len());
     let all_after = &chars_line[after_chars_trim_idx.0..after_chars_trim_idx.1];
-    let (tail, before, after, head) = get_output_chunks(&all_before, &keyword, &all_after, &config);
+    let (tail, before, after, head) = get_output_chunks(all_before, keyword, all_after, config);
     output.push_str(&format!(
         "{5}{0}{6}{5}{1}{6}{5}{2}{6}{5}{3}{6}{5}{4}{6}",
         format_tex_field(&tail),
@@ -515,7 +515,7 @@ fn format_tex_line(
         "}"
     ));
     if config.auto_ref || config.input_ref {
-        output.push_str(&format!("{}{}{}", "{", format_tex_field(&reference), "}"));
+        output.push_str(&format!("{}{}{}", "{", format_tex_field(reference), "}"));
     }
     output
 }
@@ -546,7 +546,7 @@ fn format_roff_line(
     let keyword = &line[word_ref.position..word_ref.position_end];
     let after_chars_trim_idx = (word_ref.position_end, chars_line.len());
     let all_after = &chars_line[after_chars_trim_idx.0..after_chars_trim_idx.1];
-    let (tail, before, after, head) = get_output_chunks(&all_before, &keyword, &all_after, &config);
+    let (tail, before, after, head) = get_output_chunks(all_before, keyword, all_after, config);
     output.push_str(&format!(
         " \"{}\" \"{}\" \"{}{}\" \"{}\"",
         format_roff_field(&tail),
@@ -556,7 +556,7 @@ fn format_roff_line(
         format_roff_field(&head)
     ));
     if config.auto_ref || config.input_ref {
-        output.push_str(&format!(" \"{}\"", format_roff_field(&reference)));
+        output.push_str(&format!(" \"{}\"", format_roff_field(reference)));
     }
     output
 }
diff --git a/src/uu/rm/Cargo.toml b/src/uu/rm/Cargo.toml
index 9974111aa..d84756fd3 100644
--- a/src/uu/rm/Cargo.toml
+++ b/src/uu/rm/Cargo.toml
@@ -18,10 +18,12 @@ path = "src/rm.rs"
 clap = "2.33"
 walkdir = "2.2"
 remove_dir_all = "0.5.1"
+winapi = { version="0.3", features=[] }
 
 uucore = { version=">=0.0.8", package="uucore", path="../../uucore", features=["fs"] }
 uucore_procs = { version=">=0.0.5", package="uucore_procs", path="../../uucore_procs" }
 
+
 [[bin]]
 name = "rm"
 path = "src/main.rs"
diff --git a/src/uu/rm/src/rm.rs b/src/uu/rm/src/rm.rs
index ba764034a..40a24cea7 100644
--- a/src/uu/rm/src/rm.rs
+++ b/src/uu/rm/src/rm.rs
@@ -5,7 +5,7 @@
 //  * For the full copyright and license information, please view the LICENSE
 //  * file that was distributed with this source code.
 
-// spell-checker:ignore (ToDO) bitor ulong
+// spell-checker:ignore (path) eacces
 
 #[macro_use]
 extern crate uucore;
@@ -430,9 +430,7 @@ use std::os::windows::prelude::MetadataExt;
 
 #[cfg(windows)]
 fn is_symlink_dir(metadata: &fs::Metadata) -> bool {
-    use std::os::raw::c_ulong;
-    pub type DWORD = c_ulong;
-    pub const FILE_ATTRIBUTE_DIRECTORY: DWORD = 0x10;
+    use winapi::um::winnt::FILE_ATTRIBUTE_DIRECTORY;
 
     metadata.file_type().is_symlink()
         && ((metadata.file_attributes() & FILE_ATTRIBUTE_DIRECTORY) != 0)
diff --git a/src/uu/rmdir/src/rmdir.rs b/src/uu/rmdir/src/rmdir.rs
index d13a21f60..fc22cca09 100644
--- a/src/uu/rmdir/src/rmdir.rs
+++ b/src/uu/rmdir/src/rmdir.rs
@@ -88,7 +88,7 @@ fn remove(dirs: Vec<String>, ignore: bool, parents: bool, verbose: bool) -> Resu
 
     for dir in &dirs {
         let path = Path::new(&dir[..]);
-        r = remove_dir(&path, ignore, verbose).and(r);
+        r = remove_dir(path, ignore, verbose).and(r);
         if parents {
             let mut p = path;
             while let Some(new_p) = p.parent() {
@@ -109,17 +109,14 @@ fn remove(dirs: Vec<String>, ignore: bool, parents: bool, verbose: bool) -> Resu
 }
 
 fn remove_dir(path: &Path, ignore: bool, verbose: bool) -> Result<(), i32> {
-    let mut read_dir = match fs::read_dir(path) {
-        Ok(m) => m,
-        Err(e) if e.raw_os_error() == Some(ENOTDIR) => {
+    let mut read_dir = fs::read_dir(path).map_err(|e| {
+        if e.raw_os_error() == Some(ENOTDIR) {
             show_error!("failed to remove '{}': Not a directory", path.display());
-            return Err(1);
-        }
-        Err(e) => {
+        } else {
             show_error!("reading directory '{}': {}", path.display(), e);
-            return Err(1);
         }
-    };
+        1
+    })?;
 
     let mut r = Ok(());
 
diff --git a/src/uu/shred/src/shred.rs b/src/uu/shred/src/shred.rs
index 6a43ed478..177143811 100644
--- a/src/uu/shred/src/shred.rs
+++ b/src/uu/shred/src/shred.rs
@@ -24,7 +24,7 @@ extern crate uucore;
 
 static NAME: &str = "shred";
 const BLOCK_SIZE: usize = 512;
-const NAME_CHARSET: &str = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_.";
+const NAME_CHARSET: &[u8] = b"0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_.";
 
 // Patterns as shown in the GNU coreutils shred implementation
 const PATTERNS: [&[u8]; 22] = [
@@ -89,7 +89,7 @@ impl Iterator for FilenameGenerator {
         // Make the return value, then increment
         let mut ret = String::new();
         for i in name_charset_indices.iter() {
-            let c: char = NAME_CHARSET.chars().nth(*i).unwrap();
+            let c = char::from(NAME_CHARSET[*i]);
             ret.push(c);
         }
 
@@ -163,16 +163,14 @@ impl<'a> BytesGenerator<'a> {
             return None;
         }
 
-        let this_block_size = {
-            if !self.exact {
+        let this_block_size = if !self.exact {
+            self.block_size
+        } else {
+            let bytes_left = self.total_bytes - self.bytes_generated.get();
+            if bytes_left >= self.block_size as u64 {
                 self.block_size
             } else {
-                let bytes_left = self.total_bytes - self.bytes_generated.get();
-                if bytes_left >= self.block_size as u64 {
-                    self.block_size
-                } else {
-                    (bytes_left % self.block_size as u64) as usize
-                }
+                (bytes_left % self.block_size as u64) as usize
             }
         };
 
@@ -184,12 +182,10 @@ impl<'a> BytesGenerator<'a> {
                 rng.fill(bytes);
             }
             PassType::Pattern(pattern) => {
-                let skip = {
-                    if self.bytes_generated.get() == 0 {
-                        0
-                    } else {
-                        (pattern.len() as u64 % self.bytes_generated.get()) as usize
-                    }
+                let skip = if self.bytes_generated.get() == 0 {
+                    0
+                } else {
+                    (pattern.len() as u64 % self.bytes_generated.get()) as usize
                 };
 
                 // Copy the pattern in chunks rather than simply one byte at a time
@@ -381,7 +377,7 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
 
     for path_str in matches.values_of(options::FILE).unwrap() {
         wipe_file(
-            &path_str, iterations, remove, size, exact, zero, verbose, force,
+            path_str, iterations, remove, size, exact, zero, verbose, force,
         );
     }
 
@@ -659,7 +655,7 @@ fn do_remove(path: &Path, orig_filename: &str, verbose: bool) -> Result<(), io::
         println!("{}: {}: removing", NAME, orig_filename);
     }
 
-    let renamed_path: Option<PathBuf> = wipe_name(&path, verbose);
+    let renamed_path: Option<PathBuf> = wipe_name(path, verbose);
     if let Some(rp) = renamed_path {
         fs::remove_file(rp)?;
     }
diff --git a/src/uu/shuf/src/shuf.rs b/src/uu/shuf/src/shuf.rs
index 88a47585f..2d1f558de 100644
--- a/src/uu/shuf/src/shuf.rs
+++ b/src/uu/shuf/src/shuf.rs
@@ -285,14 +285,12 @@ fn parse_range(input_range: &str) -> Result<(usize, usize), String> {
     if split.len() != 2 {
         Err(format!("invalid input range: '{}'", input_range))
     } else {
-        let begin = match split[0].parse::<usize>() {
-            Ok(m) => m,
-            Err(_) => return Err(format!("invalid input range: '{}'", split[0])),
-        };
-        let end = match split[1].parse::<usize>() {
-            Ok(m) => m,
-            Err(_) => return Err(format!("invalid input range: '{}'", split[1])),
-        };
+        let begin = split[0]
+            .parse::<usize>()
+            .map_err(|_| format!("invalid input range: '{}'", split[0]))?;
+        let end = split[1]
+            .parse::<usize>()
+            .map_err(|_| format!("invalid input range: '{}'", split[1]))?;
         Ok((begin, end + 1))
     }
 }
diff --git a/src/uu/sleep/Cargo.toml b/src/uu/sleep/Cargo.toml
index fe7ee2941..618ea7e28 100644
--- a/src/uu/sleep/Cargo.toml
+++ b/src/uu/sleep/Cargo.toml
@@ -16,7 +16,7 @@ path = "src/sleep.rs"
 
 [dependencies]
 clap = "2.33"
-uucore = { version=">=0.0.8", package="uucore", path="../../uucore", features=["parse_time"] }
+uucore = { version=">=0.0.8", package="uucore", path="../../uucore" }
 uucore_procs = { version=">=0.0.5", package="uucore_procs", path="../../uucore_procs" }
 
 [[bin]]
diff --git a/src/uu/sort/src/check.rs b/src/uu/sort/src/check.rs
index d3b9d6669..a8e5a0d9b 100644
--- a/src/uu/sort/src/check.rs
+++ b/src/uu/sort/src/check.rs
@@ -49,7 +49,7 @@ pub fn check(path: &str, settings: &GlobalSettings) -> i32 {
             let prev_last = prev_chunk.borrow_lines().last().unwrap();
             let new_first = chunk.borrow_lines().first().unwrap();
 
-            if compare_by(prev_last, new_first, &settings) == Ordering::Greater {
+            if compare_by(prev_last, new_first, settings) == Ordering::Greater {
                 if !settings.check_silent {
                     println!("sort: {}:{}: disorder: {}", path, line_idx, new_first.line);
                 }
@@ -60,7 +60,7 @@ pub fn check(path: &str, settings: &GlobalSettings) -> i32 {
 
         for (a, b) in chunk.borrow_lines().iter().tuple_windows() {
             line_idx += 1;
-            if compare_by(a, b, &settings) == Ordering::Greater {
+            if compare_by(a, b, settings) == Ordering::Greater {
                 if !settings.check_silent {
                     println!("sort: {}:{}: disorder: {}", path, line_idx, b.line);
                 }
diff --git a/src/uu/sort/src/chunks.rs b/src/uu/sort/src/chunks.rs
index dde6febd3..3d996e6d6 100644
--- a/src/uu/sort/src/chunks.rs
+++ b/src/uu/sort/src/chunks.rs
@@ -90,7 +90,7 @@ pub fn read(
         if buffer.len() < carry_over.len() {
             buffer.resize(carry_over.len() + 10 * 1024, 0);
         }
-        buffer[..carry_over.len()].copy_from_slice(&carry_over);
+        buffer[..carry_over.len()].copy_from_slice(carry_over);
         let (read, should_continue) = read_to_buffer(
             file,
             next_files,
@@ -110,7 +110,7 @@ pub fn read(
                     std::mem::transmute::<Vec<Line<'static>>, Vec<Line<'_>>>(lines)
                 };
                 let read = crash_if_err!(1, std::str::from_utf8(&buf[..read]));
-                parse_lines(read, &mut lines, separator, &settings);
+                parse_lines(read, &mut lines, separator, settings);
                 lines
             });
             sender.send(payload).unwrap();
@@ -194,7 +194,7 @@ fn read_to_buffer(
                             continue;
                         }
                     }
-                    let mut sep_iter = memchr_iter(separator, &buffer).rev();
+                    let mut sep_iter = memchr_iter(separator, buffer).rev();
                     let last_line_end = sep_iter.next();
                     if sep_iter.next().is_some() {
                         // We read enough lines.
diff --git a/src/uu/sort/src/custom_str_cmp.rs b/src/uu/sort/src/custom_str_cmp.rs
index a087a9fc2..089d33bc4 100644
--- a/src/uu/sort/src/custom_str_cmp.rs
+++ b/src/uu/sort/src/custom_str_cmp.rs
@@ -38,7 +38,7 @@ pub fn custom_str_cmp(
 ) -> Ordering {
     if !(ignore_case || ignore_non_dictionary || ignore_non_printing) {
         // There are no custom settings. Fall back to the default strcmp, which is faster.
-        return a.cmp(&b);
+        return a.cmp(b);
     }
     let mut a_chars = a
         .chars()
diff --git a/src/uu/sort/src/sort.rs b/src/uu/sort/src/sort.rs
index 70e3325ad..c2b82ee68 100644
--- a/src/uu/sort/src/sort.rs
+++ b/src/uu/sort/src/sort.rs
@@ -43,6 +43,7 @@ use std::ops::Range;
 use std::path::Path;
 use std::path::PathBuf;
 use unicode_width::UnicodeWidthStr;
+use uucore::parse_size::{parse_size, ParseSizeError};
 use uucore::InvalidEncodingHandling;
 
 static NAME: &str = "sort";
@@ -162,32 +163,29 @@ pub struct GlobalSettings {
 }
 
 impl GlobalSettings {
-    /// Interpret this `&str` as a number with an optional trailing si unit.
-    ///
-    /// If there is no trailing si unit, the implicit unit is K.
-    /// The suffix B causes the number to be interpreted as a byte count.
-    fn parse_byte_count(input: &str) -> usize {
-        const SI_UNITS: &[char] = &['B', 'K', 'M', 'G', 'T', 'P', 'E', 'Z', 'Y'];
+    /// Parse a SIZE string into a number of bytes.
+    /// A size string comprises an integer and an optional unit.
+    /// The unit may be k, K, m, M, g, G, t, T, P, E, Z, Y (powers of 1024), or b which is 1.
+    /// Default is K.
+    fn parse_byte_count(input: &str) -> Result<usize, ParseSizeError> {
+        // GNU sort (8.32)   valid: 1b,        k, K, m, M, g, G, t, T, P, E, Z, Y
+        // GNU sort (8.32) invalid:  b, B, 1B,                         p, e, z, y
+        const ALLOW_LIST: &[char] = &[
+            'b', 'k', 'K', 'm', 'M', 'g', 'G', 't', 'T', 'P', 'E', 'Z', 'Y',
+        ];
+        let mut size_string = input.trim().to_string();
 
-        let input = input.trim();
-
-        let (num_str, si_unit) =
-            if input.ends_with(|c: char| SI_UNITS.contains(&c.to_ascii_uppercase())) {
-                let mut chars = input.chars();
-                let si_suffix = chars.next_back().unwrap().to_ascii_uppercase();
-                let si_unit = SI_UNITS.iter().position(|&c| c == si_suffix).unwrap();
-                let num_str = chars.as_str();
-                (num_str, si_unit)
-            } else {
-                (input, 1)
-            };
-
-        let num_usize: usize = num_str
-            .trim()
-            .parse()
-            .unwrap_or_else(|e| crash!(1, "failed to parse buffer size `{}`: {}", num_str, e));
-
-        num_usize.saturating_mul(1000usize.saturating_pow(si_unit as u32))
+        if size_string.ends_with(|c: char| ALLOW_LIST.contains(&c) || c.is_digit(10)) {
+            // b 1, K 1024 (default)
+            if size_string.ends_with(|c: char| c.is_digit(10)) {
+                size_string.push('K');
+            } else if size_string.ends_with('b') {
+                size_string.pop();
+            }
+            parse_size(&size_string)
+        } else {
+            Err(ParseSizeError::ParseFailure("invalid suffix".to_string()))
+        }
     }
 
     fn out_writer(&self) -> BufWriter<Box<dyn Write>> {
@@ -400,9 +398,9 @@ impl<'a> Line<'a> {
         let line = self.line.replace('\t', ">");
         writeln!(writer, "{}", line)?;
 
-        let fields = tokenize(&self.line, settings.separator);
+        let fields = tokenize(self.line, settings.separator);
         for selector in settings.selectors.iter() {
-            let mut selection = selector.get_range(&self.line, Some(&fields));
+            let mut selection = selector.get_range(self.line, Some(&fields));
             match selector.settings.mode {
                 SortMode::Numeric | SortMode::HumanNumeric => {
                     // find out which range is used for numeric comparisons
@@ -756,7 +754,7 @@ impl FieldSelector {
     /// Get the selection that corresponds to this selector for the line.
     /// If needs_fields returned false, tokens may be None.
     fn get_selection<'a>(&self, line: &'a str, tokens: Option<&[Field]>) -> Selection<'a> {
-        let mut range = &line[self.get_range(&line, tokens)];
+        let mut range = &line[self.get_range(line, tokens)];
         let num_cache = if self.settings.mode == SortMode::Numeric
             || self.settings.mode == SortMode::HumanNumeric
         {
@@ -846,7 +844,7 @@ impl FieldSelector {
 
         match resolve_index(line, tokens, &self.from) {
             Resolution::StartOfChar(from) => {
-                let to = self.to.as_ref().map(|to| resolve_index(line, tokens, &to));
+                let to = self.to.as_ref().map(|to| resolve_index(line, tokens, to));
 
                 let mut range = match to {
                     Some(Resolution::StartOfChar(mut to)) => {
@@ -1176,8 +1174,10 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
 
     settings.buffer_size = matches
         .value_of(OPT_BUF_SIZE)
-        .map(GlobalSettings::parse_byte_count)
-        .unwrap_or(DEFAULT_BUF_SIZE);
+        .map_or(DEFAULT_BUF_SIZE, |s| {
+            GlobalSettings::parse_byte_count(s)
+                .unwrap_or_else(|e| crash!(2, "{}", format_error_message(e, s, OPT_BUF_SIZE)))
+        });
 
     settings.tmp_dir = matches
         .value_of(OPT_TMP_DIR)
@@ -1257,11 +1257,11 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
 fn output_sorted_lines<'a>(iter: impl Iterator<Item = &'a Line<'a>>, settings: &GlobalSettings) {
     if settings.unique {
         print_sorted(
-            iter.dedup_by(|a, b| compare_by(a, b, &settings) == Ordering::Equal),
-            &settings,
+            iter.dedup_by(|a, b| compare_by(a, b, settings) == Ordering::Equal),
+            settings,
         );
     } else {
-        print_sorted(iter, &settings);
+        print_sorted(iter, settings);
     }
 }
 
@@ -1277,16 +1277,16 @@ fn exec(files: &[String], settings: &GlobalSettings) -> i32 {
     } else {
         let mut lines = files.iter().map(open);
 
-        ext_sort(&mut lines, &settings);
+        ext_sort(&mut lines, settings);
     }
     0
 }
 
 fn sort_by<'a>(unsorted: &mut Vec<Line<'a>>, settings: &GlobalSettings) {
     if settings.stable || settings.unique {
-        unsorted.par_sort_by(|a, b| compare_by(a, b, &settings))
+        unsorted.par_sort_by(|a, b| compare_by(a, b, settings))
     } else {
-        unsorted.par_sort_unstable_by(|a, b| compare_by(a, b, &settings))
+        unsorted.par_sort_unstable_by(|a, b| compare_by(a, b, settings))
     }
 }
 
@@ -1587,6 +1587,16 @@ fn open(path: impl AsRef<OsStr>) -> Box<dyn Read + Send> {
     }
 }
 
+fn format_error_message(error: ParseSizeError, s: &str, option: &str) -> String {
+    // NOTE:
+    // GNU's sort echos affected flag, -S or --buffer-size, depending user's selection
+    // GNU's sort does distinguish between "invalid (suffix in) argument"
+    match error {
+        ParseSizeError::ParseFailure(_) => format!("invalid --{} argument '{}'", option, s),
+        ParseSizeError::SizeTooBig(_) => format!("--{} argument '{}' too large", option, s),
+    }
+}
+
 #[cfg(test)]
 mod tests {
 
@@ -1676,4 +1686,48 @@ mod tests {
         // How big is a selection? Constant cost all lines pay when we need selections.
         assert_eq!(std::mem::size_of::<Selection>(), 24);
     }
+
+    #[test]
+    fn test_parse_byte_count() {
+        let valid_input = [
+            ("0", 0),
+            ("50K", 50 * 1024),
+            ("50k", 50 * 1024),
+            ("1M", 1024 * 1024),
+            ("100M", 100 * 1024 * 1024),
+            #[cfg(not(target_pointer_width = "32"))]
+            ("1000G", 1000 * 1024 * 1024 * 1024),
+            #[cfg(not(target_pointer_width = "32"))]
+            ("10T", 10 * 1024 * 1024 * 1024 * 1024),
+            ("1b", 1),
+            ("1024b", 1024),
+            ("1024Mb", 1024 * 1024 * 1024), // NOTE: This might not be how GNU `sort` behaves for 'Mb'
+            ("1", 1024),                    // K is default
+            ("50", 50 * 1024),
+            ("K", 1024),
+            ("k", 1024),
+            ("m", 1024 * 1024),
+            #[cfg(not(target_pointer_width = "32"))]
+            ("E", 1024 * 1024 * 1024 * 1024 * 1024 * 1024),
+        ];
+        for (input, expected_output) in &valid_input {
+            assert_eq!(
+                GlobalSettings::parse_byte_count(input),
+                Ok(*expected_output)
+            );
+        }
+
+        // SizeTooBig
+        let invalid_input = ["500E", "1Y"];
+        for input in &invalid_input {
+            #[cfg(not(target_pointer_width = "128"))]
+            assert!(GlobalSettings::parse_byte_count(input).is_err());
+        }
+
+        // ParseFailure
+        let invalid_input = ["nonsense", "1B", "B", "b", "p", "e", "z", "y"];
+        for input in &invalid_input {
+            assert!(GlobalSettings::parse_byte_count(input).is_err());
+        }
+    }
 }
diff --git a/src/uu/split/src/platform/unix.rs b/src/uu/split/src/platform/unix.rs
index 20d9d637b..a115d1959 100644
--- a/src/uu/split/src/platform/unix.rs
+++ b/src/uu/split/src/platform/unix.rs
@@ -66,7 +66,7 @@ impl FilterWriter {
     /// * `filepath` - Path of the output file (forwarded to command as $FILE)
     fn new(command: &str, filepath: &str) -> FilterWriter {
         // set $FILE, save previous value (if there was one)
-        let _with_env_var_set = WithEnvVarSet::new("FILE", &filepath);
+        let _with_env_var_set = WithEnvVarSet::new("FILE", filepath);
 
         let shell_process =
             Command::new(env::var("SHELL").unwrap_or_else(|_| "/bin/sh".to_owned()))
@@ -117,7 +117,7 @@ pub fn instantiate_current_writer(
         ) as Box<dyn Write>),
         Some(ref filter_command) => BufWriter::new(Box::new(
             // spawn a shell command and write to it
-            FilterWriter::new(&filter_command, &filename),
+            FilterWriter::new(filter_command, filename),
         ) as Box<dyn Write>),
     }
 }
diff --git a/src/uu/split/src/split.rs b/src/uu/split/src/split.rs
index 6550c35ac..0d5543d8b 100644
--- a/src/uu/split/src/split.rs
+++ b/src/uu/split/src/split.rs
@@ -13,11 +13,13 @@ extern crate uucore;
 mod platform;
 
 use clap::{crate_version, App, Arg};
+use std::convert::TryFrom;
 use std::env;
 use std::fs::File;
 use std::io::{stdin, BufRead, BufReader, BufWriter, Read, Write};
 use std::path::Path;
 use std::{char, fs::remove_file};
+use uucore::parse_size::parse_size;
 
 static NAME: &str = "split";
 
@@ -231,10 +233,9 @@ struct LineSplitter {
 impl LineSplitter {
     fn new(settings: &Settings) -> LineSplitter {
         LineSplitter {
-            lines_per_split: settings
-                .strategy_param
-                .parse()
-                .unwrap_or_else(|e| crash!(1, "invalid number of lines: {}", e)),
+            lines_per_split: settings.strategy_param.parse().unwrap_or_else(|_| {
+                crash!(1, "invalid number of lines: ‘{}’", settings.strategy_param)
+            }),
         }
     }
 }
@@ -276,40 +277,14 @@ struct ByteSplitter {
 
 impl ByteSplitter {
     fn new(settings: &Settings) -> ByteSplitter {
-        // These multipliers are the same as supported by GNU coreutils.
-        let modifiers: Vec<(&str, u128)> = vec![
-            ("K", 1024u128),
-            ("M", 1024 * 1024),
-            ("G", 1024 * 1024 * 1024),
-            ("T", 1024 * 1024 * 1024 * 1024),
-            ("P", 1024 * 1024 * 1024 * 1024 * 1024),
-            ("E", 1024 * 1024 * 1024 * 1024 * 1024 * 1024),
-            ("Z", 1024 * 1024 * 1024 * 1024 * 1024 * 1024 * 1024),
-            ("Y", 1024 * 1024 * 1024 * 1024 * 1024 * 1024 * 1024 * 1024),
-            ("KB", 1000),
-            ("MB", 1000 * 1000),
-            ("GB", 1000 * 1000 * 1000),
-            ("TB", 1000 * 1000 * 1000 * 1000),
-            ("PB", 1000 * 1000 * 1000 * 1000 * 1000),
-            ("EB", 1000 * 1000 * 1000 * 1000 * 1000 * 1000),
-            ("ZB", 1000 * 1000 * 1000 * 1000 * 1000 * 1000 * 1000),
-            ("YB", 1000 * 1000 * 1000 * 1000 * 1000 * 1000 * 1000 * 1000),
-        ];
-
-        // This sequential find is acceptable since none of the modifiers are
-        // suffixes of any other modifiers, a la Huffman codes.
-        let (suffix, multiplier) = modifiers
-            .iter()
-            .find(|(suffix, _)| settings.strategy_param.ends_with(suffix))
-            .unwrap_or(&("", 1));
-
-        // Try to parse the actual numeral.
-        let n = &settings.strategy_param[0..(settings.strategy_param.len() - suffix.len())]
-            .parse::<u128>()
-            .unwrap_or_else(|e| crash!(1, "invalid number of bytes: {}", e));
+        let size_string = &settings.strategy_param;
+        let size_num = match parse_size(size_string) {
+            Ok(n) => n,
+            Err(e) => crash!(1, "invalid number of bytes: {}", e.to_string()),
+        };
 
         ByteSplitter {
-            bytes_per_split: n * multiplier,
+            bytes_per_split: u128::try_from(size_num).unwrap(),
         }
     }
 }
diff --git a/src/uu/stat/src/stat.rs b/src/uu/stat/src/stat.rs
index fa070d9b7..4e1d9d2c9 100644
--- a/src/uu/stat/src/stat.rs
+++ b/src/uu/stat/src/stat.rs
@@ -477,7 +477,7 @@ impl Stater {
             Stater::generate_tokens(&Stater::default_format(show_fs, terse, false), use_printf)
                 .unwrap()
         } else {
-            Stater::generate_tokens(&format_str, use_printf)?
+            Stater::generate_tokens(format_str, use_printf)?
         };
         let default_dev_tokens =
             Stater::generate_tokens(&Stater::default_format(show_fs, terse, true), use_printf)
diff --git a/src/uu/stdbuf/src/stdbuf.rs b/src/uu/stdbuf/src/stdbuf.rs
index 852fe3ef9..fc0c83ec8 100644
--- a/src/uu/stdbuf/src/stdbuf.rs
+++ b/src/uu/stdbuf/src/stdbuf.rs
@@ -19,6 +19,7 @@ use std::path::PathBuf;
 use std::process::Command;
 use tempfile::tempdir;
 use tempfile::TempDir;
+use uucore::parse_size::parse_size;
 use uucore::InvalidEncodingHandling;
 
 static ABOUT: &str =
@@ -55,7 +56,7 @@ const STDBUF_INJECT: &[u8] = include_bytes!(concat!(env!("OUT_DIR"), "/libstdbuf
 enum BufferType {
     Default,
     Line,
-    Size(u64),
+    Size(usize),
 }
 
 struct ProgramOptions {
@@ -69,9 +70,9 @@ impl<'a> TryFrom<&ArgMatches<'a>> for ProgramOptions {
 
     fn try_from(matches: &ArgMatches) -> Result<Self, Self::Error> {
         Ok(ProgramOptions {
-            stdin: check_option(&matches, options::INPUT)?,
-            stdout: check_option(&matches, options::OUTPUT)?,
-            stderr: check_option(&matches, options::ERROR)?,
+            stdin: check_option(matches, options::INPUT)?,
+            stdout: check_option(matches, options::OUTPUT)?,
+            stderr: check_option(matches, options::ERROR)?,
         })
     }
 }
@@ -104,41 +105,6 @@ fn preload_strings() -> (&'static str, &'static str) {
     crash!(1, "Command not supported for this operating system!")
 }
 
-fn parse_size(size: &str) -> Option<u64> {
-    let ext = size.trim_start_matches(|c: char| c.is_digit(10));
-    let num = size.trim_end_matches(char::is_alphabetic);
-    let mut recovered = num.to_owned();
-    recovered.push_str(ext);
-    if recovered != size {
-        return None;
-    }
-    let buf_size: u64 = match num.parse().ok() {
-        Some(m) => m,
-        None => return None,
-    };
-    let (power, base): (u32, u64) = match ext {
-        "" => (0, 0),
-        "KB" => (1, 1024),
-        "K" => (1, 1000),
-        "MB" => (2, 1024),
-        "M" => (2, 1000),
-        "GB" => (3, 1024),
-        "G" => (3, 1000),
-        "TB" => (4, 1024),
-        "T" => (4, 1000),
-        "PB" => (5, 1024),
-        "P" => (5, 1000),
-        "EB" => (6, 1024),
-        "E" => (6, 1000),
-        "ZB" => (7, 1024),
-        "Z" => (7, 1000),
-        "YB" => (8, 1024),
-        "Y" => (8, 1000),
-        _ => return None,
-    };
-    Some(buf_size * base.pow(power))
-}
-
 fn check_option(matches: &ArgMatches, name: &str) -> Result<BufferType, ProgramOptionsError> {
     match matches.value_of(name) {
         Some(value) => match value {
@@ -151,13 +117,10 @@ fn check_option(matches: &ArgMatches, name: &str) -> Result<BufferType, ProgramO
                     Ok(BufferType::Line)
                 }
             }
-            x => {
-                let size = match parse_size(x) {
-                    Some(m) => m,
-                    None => return Err(ProgramOptionsError(format!("invalid mode {}", x))),
-                };
-                Ok(BufferType::Size(size))
-            }
+            x => parse_size(x).map_or_else(
+                |e| crash!(125, "invalid mode {}", e),
+                |m| Ok(BufferType::Size(m)),
+            ),
         },
         None => Ok(BufferType::Default),
     }
diff --git a/src/uu/tail/src/tail.rs b/src/uu/tail/src/tail.rs
index 15a819d35..8950886a2 100644
--- a/src/uu/tail/src/tail.rs
+++ b/src/uu/tail/src/tail.rs
@@ -5,7 +5,6 @@
 //  *
 //  * For the full copyright and license information, please view the LICENSE
 //  * file that was distributed with this source code.
-//  *
 
 // spell-checker:ignore (ToDO) seekable seek'd tail'ing ringbuffer ringbuf
 
@@ -21,19 +20,18 @@ use chunks::ReverseChunks;
 
 use clap::{App, Arg};
 use std::collections::VecDeque;
-use std::error::Error;
 use std::fmt;
 use std::fs::File;
 use std::io::{stdin, stdout, BufRead, BufReader, Read, Seek, SeekFrom, Write};
 use std::path::Path;
 use std::thread::sleep;
 use std::time::Duration;
+use uucore::parse_size::{parse_size, ParseSizeError};
 use uucore::ringbuffer::RingBuffer;
 
 pub mod options {
     pub mod verbosity {
         pub static QUIET: &str = "quiet";
-        pub static SILENT: &str = "silent";
         pub static VERBOSE: &str = "verbose";
     }
     pub static BYTES: &str = "bytes";
@@ -42,13 +40,12 @@ pub mod options {
     pub static PID: &str = "pid";
     pub static SLEEP_INT: &str = "sleep-interval";
     pub static ZERO_TERM: &str = "zero-terminated";
+    pub static ARG_FILES: &str = "files";
 }
 
-static ARG_FILES: &str = "files";
-
 enum FilterMode {
-    Bytes(u64),
-    Lines(u64, u8), // (number of lines, delimiter)
+    Bytes(usize),
+    Lines(usize, u8), // (number of lines, delimiter)
 }
 
 struct Settings {
@@ -78,12 +75,14 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
     let app = App::new(executable!())
         .version(crate_version!())
         .about("output the last part of files")
+        // TODO: add usage
         .arg(
             Arg::with_name(options::BYTES)
                 .short("c")
                 .long(options::BYTES)
                 .takes_value(true)
                 .allow_hyphen_values(true)
+                .overrides_with_all(&[options::BYTES, options::LINES])
                 .help("Number of bytes to print"),
         )
         .arg(
@@ -98,6 +97,7 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
                 .long(options::LINES)
                 .takes_value(true)
                 .allow_hyphen_values(true)
+                .overrides_with_all(&[options::BYTES, options::LINES])
                 .help("Number of lines to print"),
         )
         .arg(
@@ -110,13 +110,10 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
             Arg::with_name(options::verbosity::QUIET)
                 .short("q")
                 .long(options::verbosity::QUIET)
+                .visible_alias("silent")
+                .overrides_with_all(&[options::verbosity::QUIET, options::verbosity::VERBOSE])
                 .help("never output headers giving file names"),
         )
-        .arg(
-            Arg::with_name(options::verbosity::SILENT)
-                .long(options::verbosity::SILENT)
-                .help("synonym of --quiet"),
-        )
         .arg(
             Arg::with_name(options::SLEEP_INT)
                 .short("s")
@@ -128,6 +125,7 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
             Arg::with_name(options::verbosity::VERBOSE)
                 .short("v")
                 .long(options::verbosity::VERBOSE)
+                .overrides_with_all(&[options::verbosity::QUIET, options::verbosity::VERBOSE])
                 .help("always output headers giving file names"),
         )
         .arg(
@@ -137,7 +135,7 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
                 .help("Line delimiter is NUL, not newline"),
         )
         .arg(
-            Arg::with_name(ARG_FILES)
+            Arg::with_name(options::ARG_FILES)
                 .multiple(true)
                 .takes_value(true)
                 .min_values(1),
@@ -171,38 +169,21 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
         }
     }
 
-    match matches.value_of(options::LINES) {
-        Some(n) => {
-            let mut slice: &str = n;
-            if slice.chars().next().unwrap_or('_') == '+' {
-                settings.beginning = true;
-                slice = &slice[1..];
-            }
-            match parse_size(slice) {
-                Ok(m) => settings.mode = FilterMode::Lines(m, b'\n'),
-                Err(e) => {
-                    show_error!("{}", e.to_string());
-                    return 1;
-                }
-            }
+    let mode_and_beginning = if let Some(arg) = matches.value_of(options::BYTES) {
+        match parse_num(arg) {
+            Ok((n, beginning)) => (FilterMode::Bytes(n), beginning),
+            Err(e) => crash!(1, "invalid number of bytes: {}", e.to_string()),
         }
-        None => {
-            if let Some(n) = matches.value_of(options::BYTES) {
-                let mut slice: &str = n;
-                if slice.chars().next().unwrap_or('_') == '+' {
-                    settings.beginning = true;
-                    slice = &slice[1..];
-                }
-                match parse_size(slice) {
-                    Ok(m) => settings.mode = FilterMode::Bytes(m),
-                    Err(e) => {
-                        show_error!("{}", e.to_string());
-                        return 1;
-                    }
-                }
-            }
+    } else if let Some(arg) = matches.value_of(options::LINES) {
+        match parse_num(arg) {
+            Ok((n, beginning)) => (FilterMode::Lines(n, b'\n'), beginning),
+            Err(e) => crash!(1, "invalid number of lines: {}", e.to_string()),
         }
+    } else {
+        (FilterMode::Lines(10, b'\n'), false)
     };
+    settings.mode = mode_and_beginning.0;
+    settings.beginning = mode_and_beginning.1;
 
     if matches.is_present(options::ZERO_TERM) {
         if let FilterMode::Lines(count, _) = settings.mode {
@@ -211,11 +192,10 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
     }
 
     let verbose = matches.is_present(options::verbosity::VERBOSE);
-    let quiet = matches.is_present(options::verbosity::QUIET)
-        || matches.is_present(options::verbosity::SILENT);
+    let quiet = matches.is_present(options::verbosity::QUIET);
 
     let files: Vec<String> = matches
-        .values_of(ARG_FILES)
+        .values_of(options::ARG_FILES)
         .map(|v| v.map(ToString::to_string).collect())
         .unwrap_or_default();
 
@@ -264,98 +244,6 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
     0
 }
 
-#[derive(Debug, PartialEq, Eq)]
-pub enum ParseSizeErr {
-    ParseFailure(String),
-    SizeTooBig(String),
-}
-
-impl Error for ParseSizeErr {
-    fn description(&self) -> &str {
-        match *self {
-            ParseSizeErr::ParseFailure(ref s) => &*s,
-            ParseSizeErr::SizeTooBig(ref s) => &*s,
-        }
-    }
-}
-
-impl fmt::Display for ParseSizeErr {
-    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
-        let s = match self {
-            ParseSizeErr::ParseFailure(s) => s,
-            ParseSizeErr::SizeTooBig(s) => s,
-        };
-        write!(f, "{}", s)
-    }
-}
-
-impl ParseSizeErr {
-    fn parse_failure(s: &str) -> ParseSizeErr {
-        ParseSizeErr::ParseFailure(format!("invalid size: '{}'", s))
-    }
-
-    fn size_too_big(s: &str) -> ParseSizeErr {
-        ParseSizeErr::SizeTooBig(format!(
-            "invalid size: '{}': Value too large to be stored in data type",
-            s
-        ))
-    }
-}
-
-pub type ParseSizeResult = Result<u64, ParseSizeErr>;
-
-pub fn parse_size(mut size_slice: &str) -> Result<u64, ParseSizeErr> {
-    let mut base = if size_slice.chars().last().unwrap_or('_') == 'B' {
-        size_slice = &size_slice[..size_slice.len() - 1];
-        1000u64
-    } else {
-        1024u64
-    };
-
-    let exponent = if !size_slice.is_empty() {
-        let mut has_suffix = true;
-        let exp = match size_slice.chars().last().unwrap_or('_') {
-            'K' | 'k' => 1u64,
-            'M' => 2u64,
-            'G' => 3u64,
-            'T' => 4u64,
-            'P' => 5u64,
-            'E' => 6u64,
-            'Z' | 'Y' => {
-                return Err(ParseSizeErr::size_too_big(size_slice));
-            }
-            'b' => {
-                base = 512u64;
-                1u64
-            }
-            _ => {
-                has_suffix = false;
-                0u64
-            }
-        };
-        if has_suffix {
-            size_slice = &size_slice[..size_slice.len() - 1];
-        }
-        exp
-    } else {
-        0u64
-    };
-
-    let mut multiplier = 1u64;
-    for _ in 0u64..exponent {
-        multiplier *= base;
-    }
-    if base == 1000u64 && exponent == 0u64 {
-        // sole B is not a valid suffix
-        Err(ParseSizeErr::parse_failure(size_slice))
-    } else {
-        let value: Option<i64> = size_slice.parse().ok();
-        value
-            .map(|v| Ok((multiplier as i64 * v.abs()) as u64))
-            .unwrap_or_else(|| Err(ParseSizeErr::parse_failure(size_slice)))
-    }
-}
-
 fn follow<T: Read>(readers: &mut [BufReader<T>], filenames: &[String], settings: &Settings) {
     assert!(settings.follow);
     let mut last = readers.len() - 1;
@@ -469,7 +357,7 @@ fn bounded_tail(file: &mut File, settings: &Settings) {
 /// If any element of `iter` is an [`Err`], then this function panics.
 fn unbounded_tail_collect<T, E>(
     iter: impl Iterator<Item = Result<T, E>>,
-    count: u64,
+    count: usize,
     beginning: bool,
 ) -> VecDeque<T>
 where
@@ -514,3 +402,22 @@ fn print_byte<T: Write>(stdout: &mut T, ch: u8) {
         crash!(1, "{}", err);
     }
 }
+
+fn parse_num(src: &str) -> Result<(usize, bool), ParseSizeError> {
+    let mut size_string = src.trim();
+    let mut starting_with = false;
+
+    if let Some(c) = size_string.chars().next() {
+        if c == '+' || c == '-' {
+            // tail: '-' is not documented (8.32 man pages)
+            size_string = &size_string[1..];
+            if c == '+' {
+                starting_with = true;
+            }
+        }
+    } else {
+        return Err(ParseSizeError::ParseFailure(src.to_string()));
+    }
+
+    parse_size(size_string).map(|n| (n, starting_with))
+}
diff --git a/src/uu/timeout/Cargo.toml b/src/uu/timeout/Cargo.toml
index 206a98c08..a46b029bd 100644
--- a/src/uu/timeout/Cargo.toml
+++ b/src/uu/timeout/Cargo.toml
@@ -16,9 +16,8 @@ path = "src/timeout.rs"
 
 [dependencies]
 clap = "2.33"
-getopts = "0.2.18"
 libc = "0.2.42"
-uucore = { version=">=0.0.8", package="uucore", path="../../uucore", features=["parse_time", "process", "signals"] }
+uucore = { version=">=0.0.8", package="uucore", path="../../uucore", features=["process", "signals"] }
 uucore_procs = { version=">=0.0.5", package="uucore_procs", path="../../uucore_procs" }
 
 
diff --git a/src/uu/timeout/src/timeout.rs b/src/uu/timeout/src/timeout.rs
index 4ef9b2331..afe560ee5 100644
--- a/src/uu/timeout/src/timeout.rs
+++ b/src/uu/timeout/src/timeout.rs
@@ -55,7 +55,7 @@ impl Config {
     fn from(options: clap::ArgMatches) -> Config {
         let signal = match options.value_of(options::SIGNAL) {
             Some(signal_) => {
-                let signal_result = signal_by_name_or_value(&signal_);
+                let signal_result = signal_by_name_or_value(signal_);
                 match signal_result {
                     None => {
                         unreachable!("invalid signal '{}'", signal_);
@@ -67,7 +67,7 @@ impl Config {
         };
 
         let kill_after: Duration = match options.value_of(options::KILL_AFTER) {
-            Some(time) => uucore::parse_time::from_str(&time).unwrap(),
+            Some(time) => uucore::parse_time::from_str(time).unwrap(),
             None => Duration::new(0, 0),
         };
 
diff --git a/src/uu/tr/src/expand.rs b/src/uu/tr/src/expand.rs
index 7d0c61c30..5d960921e 100644
--- a/src/uu/tr/src/expand.rs
+++ b/src/uu/tr/src/expand.rs
@@ -22,14 +22,15 @@ use std::ops::RangeInclusive;
 /// character; octal escape sequences consume 1 to 3 octal digits.
 #[inline]
 fn parse_sequence(s: &str) -> (char, usize) {
-    let c = s.chars().next().expect("invalid escape: empty string");
+    let mut s = s.chars();
+    let c = s.next().expect("invalid escape: empty string");
 
     if ('0'..='7').contains(&c) {
         let mut v = c.to_digit(8).unwrap();
         let mut consumed = 1;
         let bits_per_digit = 3;
 
-        for c in s.chars().skip(1).take(2) {
+        for c in s.take(2) {
             match c.to_digit(8) {
                 Some(c) => {
                     v = (v << bits_per_digit) | c;
diff --git a/src/uu/truncate/src/truncate.rs b/src/uu/truncate/src/truncate.rs
index 8e785ad21..f81a95ab2 100644
--- a/src/uu/truncate/src/truncate.rs
+++ b/src/uu/truncate/src/truncate.rs
@@ -11,19 +11,21 @@
 extern crate uucore;
 
 use clap::{crate_version, App, Arg};
+use std::convert::TryFrom;
 use std::fs::{metadata, OpenOptions};
 use std::io::ErrorKind;
 use std::path::Path;
+use uucore::parse_size::{parse_size, ParseSizeError};
 
 #[derive(Debug, Eq, PartialEq)]
 enum TruncateMode {
-    Absolute(u64),
-    Extend(u64),
-    Reduce(u64),
-    AtMost(u64),
-    AtLeast(u64),
-    RoundDown(u64),
-    RoundUp(u64),
+    Absolute(usize),
+    Extend(usize),
+    Reduce(usize),
+    AtMost(usize),
+    AtLeast(usize),
+    RoundDown(usize),
+    RoundUp(usize),
 }
 
 impl TruncateMode {
@@ -38,7 +40,7 @@ impl TruncateMode {
     /// let fsize = 10;
     /// assert_eq!(mode.to_size(fsize), 15);
     /// ```
-    fn to_size(&self, fsize: u64) -> u64 {
+    fn to_size(&self, fsize: usize) -> usize {
         match self {
             TruncateMode::Absolute(size) => *size,
             TruncateMode::Extend(size) => fsize + size,
@@ -58,10 +60,9 @@ pub mod options {
     pub static NO_CREATE: &str = "no-create";
     pub static REFERENCE: &str = "reference";
     pub static SIZE: &str = "size";
+    pub static ARG_FILES: &str = "files";
 }
 
-static ARG_FILES: &str = "files";
-
 fn get_usage() -> String {
     format!("{0} [OPTION]... [FILE]...", executable!())
 }
@@ -113,21 +114,28 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
             Arg::with_name(options::REFERENCE)
             .short("r")
             .long(options::REFERENCE)
+            .required_unless(options::SIZE)
             .help("base the size of each file on the size of RFILE")
             .value_name("RFILE")
         )
         .arg(
             Arg::with_name(options::SIZE)
             .short("s")
-            .long("size")
+            .long(options::SIZE)
+            .required_unless(options::REFERENCE)
             .help("set or adjust the size of each file according to SIZE, which is in bytes unless --io-blocks is specified")
             .value_name("SIZE")
         )
-        .arg(Arg::with_name(ARG_FILES).multiple(true).takes_value(true).min_values(1))
+        .arg(Arg::with_name(options::ARG_FILES)
+             .value_name("FILE")
+             .multiple(true)
+             .takes_value(true)
+             .required(true)
+             .min_values(1))
         .get_matches_from(args);
 
     let files: Vec<String> = matches
-        .values_of(ARG_FILES)
+        .values_of(options::ARG_FILES)
         .map(|v| v.map(ToString::to_string).collect())
         .unwrap_or_default();
 
@@ -149,8 +157,8 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
                     crash!(
                         1,
                         "cannot stat '{}': No such file or directory",
-                        reference.unwrap()
-                    );
+                        reference.unwrap_or_else(|| "".to_string())
+                    ); // TODO: fix '--no-create' see test_reference and test_truncate_bytes_size
                 }
                 _ => crash!(1, "{}", e.to_string()),
             }
@@ -172,10 +180,10 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
 ///
 /// If the file could not be opened, or there was a problem setting the
 /// size of the file.
-fn file_truncate(filename: &str, create: bool, size: u64) -> std::io::Result<()> {
+fn file_truncate(filename: &str, create: bool, size: usize) -> std::io::Result<()> {
     let path = Path::new(filename);
     let f = OpenOptions::new().write(true).create(create).open(path)?;
-    f.set_len(size)
+    f.set_len(u64::try_from(size).unwrap())
 }
 
 /// Truncate files to a size relative to a given file.
@@ -206,9 +214,9 @@ fn truncate_reference_and_size(
             }
             _ => m,
         },
-        Err(_) => crash!(1, "Invalid number: ‘{}’", size_string),
+        Err(e) => crash!(1, "Invalid number: {}", e.to_string()),
     };
-    let fsize = metadata(rfilename)?.len();
+    let fsize = usize::try_from(metadata(rfilename)?.len()).unwrap();
     let tsize = mode.to_size(fsize);
     for filename in &filenames {
         file_truncate(filename, create, tsize)?;
@@ -232,7 +240,7 @@ fn truncate_reference_file_only(
     filenames: Vec<String>,
     create: bool,
 ) -> std::io::Result<()> {
-    let tsize = metadata(rfilename)?.len();
+    let tsize = usize::try_from(metadata(rfilename)?.len()).unwrap();
     for filename in &filenames {
         file_truncate(filename, create, tsize)?;
     }
@@ -261,10 +269,10 @@ fn truncate_size_only(
 ) -> std::io::Result<()> {
     let mode = match parse_mode_and_size(size_string) {
         Ok(m) => m,
-        Err(_) => crash!(1, "Invalid number: ‘{}’", size_string),
+        Err(e) => crash!(1, "Invalid number: {}", e.to_string()),
     };
     for filename in &filenames {
-        let fsize = metadata(filename).map(|m| m.len()).unwrap_or(0);
+        let fsize = usize::try_from(metadata(filename)?.len()).unwrap();
         let tsize = mode.to_size(fsize);
         file_truncate(filename, create, tsize)?;
     }
@@ -290,7 +298,7 @@ fn truncate(
         }
         (Some(rfilename), None) => truncate_reference_file_only(&rfilename, filenames, create),
         (None, Some(size_string)) => truncate_size_only(&size_string, filenames, create),
-        (None, None) => crash!(1, "you must specify either --reference or --size"),
+        (None, None) => crash!(1, "you must specify either --reference or --size"), // this case cannot happen anymore because it's handled by clap
     }
 }
 
@@ -317,117 +325,35 @@ fn is_modifier(c: char) -> bool {
 /// ```rust,ignore
 /// assert_eq!(parse_mode_and_size("+123"), (TruncateMode::Extend, 123));
 /// ```
-fn parse_mode_and_size(size_string: &str) -> Result<TruncateMode, ()> {
+fn parse_mode_and_size(size_string: &str) -> Result<TruncateMode, ParseSizeError> {
     // Trim any whitespace.
-    let size_string = size_string.trim();
+    let mut size_string = size_string.trim();
 
     // Get the modifier character from the size string, if any. For
     // example, if the argument is "+123", then the modifier is '+'.
-    let c = size_string.chars().next().unwrap();
-    let size_string = if is_modifier(c) {
-        &size_string[1..]
+    if let Some(c) = size_string.chars().next() {
+        if is_modifier(c) {
+            size_string = &size_string[1..];
+        }
+        parse_size(size_string).map(match c {
+            '+' => TruncateMode::Extend,
+            '-' => TruncateMode::Reduce,
+            '<' => TruncateMode::AtMost,
+            '>' => TruncateMode::AtLeast,
+            '/' => TruncateMode::RoundDown,
+            '%' => TruncateMode::RoundUp,
+            _ => TruncateMode::Absolute,
+        })
     } else {
-        size_string
-    };
-    parse_size(size_string).map(match c {
-        '+' => TruncateMode::Extend,
-        '-' => TruncateMode::Reduce,
-        '<' => TruncateMode::AtMost,
-        '>' => TruncateMode::AtLeast,
-        '/' => TruncateMode::RoundDown,
-        '%' => TruncateMode::RoundUp,
-        _ => TruncateMode::Absolute,
-    })
-}
-
-/// Parse a size string into a number of bytes.
-///
-/// A size string comprises an integer and an optional unit. The unit
-/// may be K, M, G, T, P, E, Z, or Y (powers of 1024) or KB, MB,
-/// etc. (powers of 1000).
-///
-/// # Errors
-///
-/// This function returns an error if the string does not begin with a
-/// numeral, or if the unit is not one of the supported units described
-/// in the preceding section.
-///
-/// # Examples
-///
-/// ```rust,ignore
-/// assert_eq!(parse_size("123").unwrap(), 123);
-/// assert_eq!(parse_size("123K").unwrap(), 123 * 1024);
-/// assert_eq!(parse_size("123KB").unwrap(), 123 * 1000);
-/// ```
-fn parse_size(size: &str) -> Result<u64, ()> {
-    // Get the numeric part of the size argument. For example, if the
-    // argument is "123K", then the numeric part is "123".
-    let numeric_string: String = size.chars().take_while(|c| c.is_digit(10)).collect();
-    let number: u64 = match numeric_string.parse() {
-        Ok(n) => n,
-        Err(_) => return Err(()),
-    };
-
-    // Get the alphabetic units part of the size argument and compute
-    // the factor it represents. For example, if the argument is "123K",
-    // then the unit part is "K" and the factor is 1024. This may be the
-    // empty string, in which case, the factor is 1.
-    let n = numeric_string.len();
-    let (base, exponent): (u64, u32) = match &size[n..] {
-        "" => (1, 0),
-        "K" | "k" => (1024, 1),
-        "M" | "m" => (1024, 2),
-        "G" | "g" => (1024, 3),
-        "T" | "t" => (1024, 4),
-        "P" | "p" => (1024, 5),
-        "E" | "e" => (1024, 6),
-        "Z" | "z" => (1024, 7),
-        "Y" | "y" => (1024, 8),
-        "KB" | "kB" => (1000, 1),
-        "MB" | "mB" => (1000, 2),
-        "GB" | "gB" => (1000, 3),
-        "TB" | "tB" => (1000, 4),
-        "PB" | "pB" => (1000, 5),
-        "EB" | "eB" => (1000, 6),
-        "ZB" | "zB" => (1000, 7),
-        "YB" | "yB" => (1000, 8),
-        _ => return Err(()),
-    };
-    let factor = base.pow(exponent);
-    Ok(number * factor)
+        Err(ParseSizeError::ParseFailure(size_string.to_string()))
+    }
 }
 
 #[cfg(test)]
 mod tests {
     use crate::parse_mode_and_size;
-    use crate::parse_size;
     use crate::TruncateMode;
 
-    #[test]
-    fn test_parse_size_zero() {
-        assert_eq!(parse_size("0").unwrap(), 0);
-        assert_eq!(parse_size("0K").unwrap(), 0);
-        assert_eq!(parse_size("0KB").unwrap(), 0);
-    }
-
-    #[test]
-    fn test_parse_size_without_factor() {
-        assert_eq!(parse_size("123").unwrap(), 123);
-    }
-
-    #[test]
-    fn test_parse_size_kilobytes() {
-        assert_eq!(parse_size("123K").unwrap(), 123 * 1024);
-        assert_eq!(parse_size("123KB").unwrap(), 123 * 1000);
-    }
-
-    #[test]
-    fn test_parse_size_megabytes() {
-        assert_eq!(parse_size("123").unwrap(), 123);
-        assert_eq!(parse_size("123M").unwrap(), 123 * 1024 * 1024);
-        assert_eq!(parse_size("123MB").unwrap(), 123 * 1000 * 1000);
-    }
-
     #[test]
     fn test_parse_mode_and_size() {
         assert_eq!(parse_mode_and_size("10"), Ok(TruncateMode::Absolute(10)));
diff --git a/src/uu/tty/Cargo.toml b/src/uu/tty/Cargo.toml
index 7be27a900..49b7669df 100644
--- a/src/uu/tty/Cargo.toml
+++ b/src/uu/tty/Cargo.toml
@@ -17,6 +17,7 @@ path = "src/tty.rs"
 [dependencies]
 clap = "2.33"
 libc = "0.2.42"
+atty = "0.2"
 uucore = { version=">=0.0.8", package="uucore", path="../../uucore", features=["fs"] }
 uucore_procs = { version=">=0.0.5", package="uucore_procs", path="../../uucore_procs" }
 
diff --git a/src/uu/tty/src/tty.rs b/src/uu/tty/src/tty.rs
index 074bcf182..edcdf091e 100644
--- a/src/uu/tty/src/tty.rs
+++ b/src/uu/tty/src/tty.rs
@@ -14,7 +14,6 @@ extern crate uucore;
 
 use clap::{crate_version, App, Arg};
 use std::ffi::CStr;
-use uucore::fs::is_stdin_interactive;
 use uucore::InvalidEncodingHandling;
 
 static ABOUT: &str = "Print the file name of the terminal connected to standard input.";
@@ -67,7 +66,7 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
         }
     }
 
-    if is_stdin_interactive() {
+    if atty::is(atty::Stream::Stdin) {
         libc::EXIT_SUCCESS
     } else {
         libc::EXIT_FAILURE
diff --git a/src/uu/wc/src/wc.rs b/src/uu/wc/src/wc.rs
index 031c25739..d1e1f75ca 100644
--- a/src/uu/wc/src/wc.rs
+++ b/src/uu/wc/src/wc.rs
@@ -374,8 +374,8 @@ fn wc(inputs: Vec<Input>, settings: &Settings) -> Result<(), u32> {
     let num_inputs = inputs.len();
 
     for input in &inputs {
-        let word_count = word_count_from_input(&input, settings).unwrap_or_else(|err| {
-            show_error(&input, err);
+        let word_count = word_count_from_input(input, settings).unwrap_or_else(|err| {
+            show_error(input, err);
             error_count += 1;
             WordCount::default()
         });
diff --git a/src/uu/who/src/who.rs b/src/uu/who/src/who.rs
index d2f64aa94..44f565438 100644
--- a/src/uu/who/src/who.rs
+++ b/src/uu/who/src/who.rs
@@ -179,124 +179,58 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
     // Ignored for 'who am i'.
     let short_list = matches.is_present(options::COUNT);
 
-    // If true, display only name, line, and time fields.
-    let mut short_output = false;
-
-    // If true, display the hours:minutes since each user has touched
-    // the keyboard, or "." if within the last minute, or "old" if
-    // not within the last day.
-    let mut include_idle = false;
+    let all = matches.is_present(options::ALL);
 
     // If true, display a line at the top describing each field.
     let include_heading = matches.is_present(options::HEADING);
 
     // If true, display a '+' for each user if mesg y, a '-' if mesg n,
     // or a '?' if their tty cannot be statted.
-    let include_mesg = matches.is_present(options::ALL)
-        || matches.is_present(options::MESG)
-        || matches.is_present("w");
-
-    // If true, display process termination & exit status.
-    let mut include_exit = false;
+    let include_mesg = all || matches.is_present(options::MESG) || matches.is_present("w");
 
     // If true, display the last boot time.
-    let mut need_boottime = false;
+    let need_boottime = all || matches.is_present(options::BOOT);
 
     // If true, display dead processes.
-    let mut need_deadprocs = false;
+    let need_deadprocs = all || matches.is_present(options::DEAD);
 
     // If true, display processes waiting for user login.
-    let mut need_login = false;
+    let need_login = all || matches.is_present(options::LOGIN);
 
     // If true, display processes started by init.
-    let mut need_initspawn = false;
+    let need_initspawn = all || matches.is_present(options::PROCESS);
 
     // If true, display the last clock change.
-    let mut need_clockchange = false;
+    let need_clockchange = all || matches.is_present(options::TIME);
 
     // If true, display the current runlevel.
-    let mut need_runlevel = false;
+    let need_runlevel = all || matches.is_present(options::RUNLEVEL);
+
+    let use_defaults = !(all
+        || need_boottime
+        || need_deadprocs
+        || need_login
+        || need_initspawn
+        || need_runlevel
+        || need_clockchange
+        || matches.is_present(options::USERS));
 
     // If true, display user processes.
-    let mut need_users = false;
+    let need_users = all || matches.is_present(options::USERS) || use_defaults;
+
+    // If true, display the hours:minutes since each user has touched
+    // the keyboard, or "." if within the last minute, or "old" if
+    // not within the last day.
+    let include_idle = need_deadprocs || need_login || need_runlevel || need_users;
+
+    // If true, display process termination & exit status.
+    let include_exit = need_deadprocs;
+
+    // If true, display only name, line, and time fields.
+    let short_output = !include_exit && use_defaults;
 
     // If true, display info only for the controlling tty.
-    let mut my_line_only = false;
-
-    let mut assumptions = true;
-
-    #[allow(clippy::useless_let_if_seq)]
-    {
-        if matches.is_present(options::ALL) {
-            need_boottime = true;
-            need_deadprocs = true;
-            need_login = true;
-            need_initspawn = true;
-            need_runlevel = true;
-            need_clockchange = true;
-            need_users = true;
-            include_idle = true;
-            include_exit = true;
-            assumptions = false;
-        }
-
-        if matches.is_present(options::BOOT) {
-            need_boottime = true;
-            assumptions = false;
-        }
-
-        if matches.is_present(options::DEAD) {
-            need_deadprocs = true;
-            include_idle = true;
-            include_exit = true;
-            assumptions = false;
-        }
-
-        if matches.is_present(options::LOGIN) {
-            need_login = true;
-            include_idle = true;
-            assumptions = false;
-        }
-
-        if matches.is_present(options::ONLY_HOSTNAME_USER) || files.len() == 2 {
-            my_line_only = true;
-        }
-
-        if matches.is_present(options::PROCESS) {
-            need_initspawn = true;
-            assumptions = false;
-        }
-
-        if matches.is_present(options::RUNLEVEL) {
-            need_runlevel = true;
-            include_idle = true;
-            assumptions = false;
-        }
-
-        if matches.is_present(options::SHORT) {
-            short_output = true;
-        }
-
-        if matches.is_present(options::TIME) {
-            need_clockchange = true;
-            assumptions = false;
-        }
-
-        if matches.is_present(options::USERS) {
-            need_users = true;
-            include_idle = true;
-            assumptions = false;
-        }
-
-        if assumptions {
-            need_users = true;
-            short_output = true;
-        }
-
-        if include_exit {
-            short_output = false;
-        }
-    }
+    let my_line_only = matches.is_present(options::ONLY_HOSTNAME_USER) || files.len() == 2;
 
     let mut who = Who {
         do_lookup,
diff --git a/src/uu/whoami/Cargo.toml b/src/uu/whoami/Cargo.toml
index f8dc01440..28670c8b5 100644
--- a/src/uu/whoami/Cargo.toml
+++ b/src/uu/whoami/Cargo.toml
@@ -20,7 +20,6 @@ uucore = { version=">=0.0.8", package="uucore", path="../../uucore", features=["
 uucore_procs = { version=">=0.0.5", package="uucore_procs", path="../../uucore_procs" }
 
 [target.'cfg(target_os = "windows")'.dependencies]
-advapi32-sys = "0.2.0"
 winapi = { version = "0.3", features = ["lmcons"] }
 
 [[bin]]
diff --git a/src/uu/whoami/src/platform/windows.rs b/src/uu/whoami/src/platform/windows.rs
index 5d648877b..3fe8eb1e7 100644
--- a/src/uu/whoami/src/platform/windows.rs
+++ b/src/uu/whoami/src/platform/windows.rs
@@ -11,7 +11,7 @@ extern crate winapi;
 
 use self::winapi::shared::lmcons;
 use self::winapi::shared::minwindef;
-use self::winapi::um::winnt;
+use self::winapi::um::{winbase, winnt};
 use std::io::{Error, Result};
 use std::mem;
 use uucore::wide::FromWide;
@@ -20,7 +20,7 @@ pub unsafe fn get_username() -> Result<String> {
     #[allow(deprecated)]
     let mut buffer: [winnt::WCHAR; lmcons::UNLEN as usize + 1] = mem::uninitialized();
     let mut len = buffer.len() as minwindef::DWORD;
-    if advapi32::GetUserNameW(buffer.as_mut_ptr(), &mut len) == 0 {
+    if winbase::GetUserNameW(buffer.as_mut_ptr(), &mut len) == 0 {
         return Err(Error::last_os_error());
     }
     let username = String::from_wide(&buffer[..len as usize - 1]);
diff --git a/src/uucore/Cargo.toml b/src/uucore/Cargo.toml
index 482252680..0c11d2c15 100644
--- a/src/uucore/Cargo.toml
+++ b/src/uucore/Cargo.toml
@@ -44,7 +44,6 @@ entries = ["libc"]
 fs = ["libc"]
 fsext = ["libc", "time"]
 mode = ["libc"]
-parse_time = []
 perms = ["libc"]
 process = ["libc"]
 ringbuffer = []
diff --git a/src/uucore/src/lib/features.rs b/src/uucore/src/lib/features.rs
index 310a41fe1..c1e1ec31e 100644
--- a/src/uucore/src/lib/features.rs
+++ b/src/uucore/src/lib/features.rs
@@ -6,8 +6,6 @@ pub mod encoding;
 pub mod fs;
 #[cfg(feature = "fsext")]
 pub mod fsext;
-#[cfg(feature = "parse_time")]
-pub mod parse_time;
 #[cfg(feature = "ringbuffer")]
 pub mod ringbuffer;
 #[cfg(feature = "zero-copy")]
diff --git a/src/uucore/src/lib/features/entries.rs b/src/uucore/src/lib/features/entries.rs
index 2d5b44362..d814e049b 100644
--- a/src/uucore/src/lib/features/entries.rs
+++ b/src/uucore/src/lib/features/entries.rs
@@ -94,16 +94,21 @@ pub fn get_groups() -> IOResult<Vec<gid_t>> {
 /// groups is the same (in the mathematical sense of ``set''). (The
 /// history of a process and its parents could affect the details of
 /// the result.)
+#[cfg(all(unix, feature = "process"))]
 pub fn get_groups_gnu(arg_id: Option<u32>) -> IOResult<Vec<gid_t>> {
-    let mut groups = get_groups()?;
+    let groups = get_groups()?;
     let egid = arg_id.unwrap_or_else(crate::features::process::getegid);
-    if !groups.is_empty() && *groups.first().unwrap() == egid {
-        return Ok(groups);
-    } else if let Some(index) = groups.iter().position(|&x| x == egid) {
-        groups.remove(index);
+    Ok(sort_groups(groups, egid))
+}
+
+#[cfg(all(unix, feature = "process"))]
+fn sort_groups(mut groups: Vec<gid_t>, egid: gid_t) -> Vec<gid_t> {
+    if let Some(index) = groups.iter().position(|&x| x == egid) {
+        groups[..=index].rotate_right(1);
+    } else {
+        groups.insert(0, egid);
     }
-    groups.insert(0, egid);
-    Ok(groups)
+    groups
 }
 
 #[derive(Copy, Clone)]
@@ -315,6 +320,15 @@ pub fn grp2gid(name: &str) -> IOResult<gid_t> {
 mod test {
     use super::*;
 
+    #[test]
+    fn test_sort_groups() {
+        assert_eq!(sort_groups(vec![1, 2, 3], 4), vec![4, 1, 2, 3]);
+        assert_eq!(sort_groups(vec![1, 2, 3], 3), vec![3, 1, 2]);
+        assert_eq!(sort_groups(vec![1, 2, 3], 2), vec![2, 1, 3]);
+        assert_eq!(sort_groups(vec![1, 2, 3], 1), vec![1, 2, 3]);
+        assert_eq!(sort_groups(vec![1, 2, 3], 0), vec![0, 1, 2, 3]);
+    }
+
     #[test]
     fn test_entries_get_groups_gnu() {
         if let Ok(mut groups) = get_groups() {
diff --git a/src/uucore/src/lib/features/fs.rs b/src/uucore/src/lib/features/fs.rs
index 38cdbef94..36bdbfed0 100644
--- a/src/uucore/src/lib/features/fs.rs
+++ b/src/uucore/src/lib/features/fs.rs
@@ -113,22 +113,14 @@ fn resolve<P: AsRef<Path>>(original: P) -> IOResult<PathBuf> {
             ));
         }
 
-        match fs::symlink_metadata(&result) {
-            Err(e) => return Err(e),
-            Ok(ref m) if !m.file_type().is_symlink() => break,
-            Ok(..) => {
-                followed += 1;
-                match fs::read_link(&result) {
-                    Ok(path) => {
-                        result.pop();
-                        result.push(path);
-                    }
-                    Err(e) => {
-                        return Err(e);
-                    }
-                }
-            }
+        if !fs::symlink_metadata(&result)?.file_type().is_symlink() {
+            break;
         }
+
+        followed += 1;
+        let path = fs::read_link(&result)?;
+        result.pop();
+        result.push(path);
     }
     Ok(result)
 }
@@ -193,10 +185,8 @@ pub fn canonicalize<P: AsRef<Path>>(original: P, can_mode: CanonicalizeMode) ->
             }
 
             match resolve(&result) {
-                Err(e) => match can_mode {
-                    CanonicalizeMode::Missing => continue,
-                    _ => return Err(e),
-                },
+                Err(_) if can_mode == CanonicalizeMode::Missing => continue,
+                Err(e) => return Err(e),
                 Ok(path) => {
                     result.pop();
                     result.push(path);
@@ -211,65 +201,19 @@ pub fn canonicalize<P: AsRef<Path>>(original: P, can_mode: CanonicalizeMode) ->
         }
 
         match resolve(&result) {
-            Err(e) => {
-                if can_mode == CanonicalizeMode::Existing {
-                    return Err(e);
-                }
+            Err(e) if can_mode == CanonicalizeMode::Existing => {
+                return Err(e);
             }
             Ok(path) => {
                 result.pop();
                 result.push(path);
             }
+            Err(_) => (),
         }
     }
     Ok(result)
 }
 
-#[cfg(unix)]
-pub fn is_stdin_interactive() -> bool {
-    unsafe { libc::isatty(libc::STDIN_FILENO) == 1 }
-}
-
-#[cfg(windows)]
-pub fn is_stdin_interactive() -> bool {
-    false
-}
-
-#[cfg(target_os = "redox")]
-pub fn is_stdin_interactive() -> bool {
-    termion::is_tty(&io::stdin())
-}
-
-#[cfg(unix)]
-pub fn is_stdout_interactive() -> bool {
-    unsafe { libc::isatty(libc::STDOUT_FILENO) == 1 }
-}
-
-#[cfg(windows)]
-pub fn is_stdout_interactive() -> bool {
-    false
-}
-
-#[cfg(target_os = "redox")]
-pub fn is_stdout_interactive() -> bool {
-    termion::is_tty(&io::stdout())
-}
-
-#[cfg(unix)]
-pub fn is_stderr_interactive() -> bool {
-    unsafe { libc::isatty(libc::STDERR_FILENO) == 1 }
-}
-
-#[cfg(windows)]
-pub fn is_stderr_interactive() -> bool {
-    false
-}
-
-#[cfg(target_os = "redox")]
-pub fn is_stderr_interactive() -> bool {
-    termion::is_tty(&io::stderr())
-}
-
 #[cfg(not(unix))]
 #[allow(unused_variables)]
 pub fn display_permissions(metadata: &fs::Metadata, display_file_type: bool) -> String {
diff --git a/src/uucore/src/lib/features/mode.rs b/src/uucore/src/lib/features/mode.rs
index 4fb5a6509..fe109d73d 100644
--- a/src/uucore/src/lib/features/mode.rs
+++ b/src/uucore/src/lib/features/mode.rs
@@ -89,19 +89,19 @@ fn parse_levels(mode: &str) -> (u32, usize) {
 }
 
 fn parse_op(mode: &str, default: Option<char>) -> Result<(char, usize), String> {
-    match mode.chars().next() {
-        Some(ch) => match ch {
-            '+' | '-' | '=' => Ok((ch, 1)),
-            _ => match default {
-                Some(ch) => Ok((ch, 0)),
-                None => Err(format!(
-                    "invalid operator (expected +, -, or =, but found {})",
-                    ch
-                )),
-            },
-        },
-        None => Err("unexpected end of mode".to_owned()),
-    }
+    let ch = mode
+        .chars()
+        .next()
+        .ok_or_else(|| "unexpected end of mode".to_owned())?;
+    Ok(match ch {
+        '+' | '-' | '=' => (ch, 1),
+        _ => {
+            let ch = default.ok_or_else(|| {
+                format!("invalid operator (expected +, -, or =, but found {})", ch)
+            })?;
+            (ch, 0)
+        }
+    })
 }
 
 fn parse_change(mode: &str, fperm: u32, considering_dir: bool) -> (u32, usize) {
diff --git a/src/uucore/src/lib/features/perms.rs b/src/uucore/src/lib/features/perms.rs
index eb6cca102..89c30b53b 100644
--- a/src/uucore/src/lib/features/perms.rs
+++ b/src/uucore/src/lib/features/perms.rs
@@ -92,7 +92,7 @@ pub fn wrap_chgrp<P: AsRef<Path>>(
             out = format!(
                 "group of '{}' retained as {}",
                 path.display(),
-                entries::gid2grp(dest_gid).unwrap()
+                entries::gid2grp(dest_gid).unwrap_or_default()
             );
         }
     }
diff --git a/src/uucore/src/lib/features/utmpx.rs b/src/uucore/src/lib/features/utmpx.rs
index a794b01da..5077d9e59 100644
--- a/src/uucore/src/lib/features/utmpx.rs
+++ b/src/uucore/src/lib/features/utmpx.rs
@@ -207,7 +207,7 @@ impl Utmpx {
                 flags: AI_CANONNAME,
                 ..AddrInfoHints::default()
             };
-            let sockets = getaddrinfo(Some(&hostname), None, Some(hints))
+            let sockets = getaddrinfo(Some(hostname), None, Some(hints))
                 .unwrap()
                 .collect::<IOResult<Vec<_>>>()?;
             for socket in sockets {
diff --git a/src/uucore/src/lib/lib.rs b/src/uucore/src/lib/lib.rs
index 0b0d0fddf..f765b7b3e 100644
--- a/src/uucore/src/lib/lib.rs
+++ b/src/uucore/src/lib/lib.rs
@@ -19,10 +19,10 @@ pub extern crate winapi;
 
 //## internal modules
 
-mod macros; // crate macros (macro_rules-type; exported to `crate::...`)
-
 mod features; // feature-gated code modules
+mod macros; // crate macros (macro_rules-type; exported to `crate::...`)
 mod mods; // core cross-platform modules
+mod parser; // string parsing modules
 
 // * cross-platform modules
 pub use crate::mods::backup_control;
@@ -31,6 +31,10 @@ pub use crate::mods::os;
 pub use crate::mods::panic;
 pub use crate::mods::ranges;
 
+// * string parsing modules
+pub use crate::parser::parse_size;
+pub use crate::parser::parse_time;
+
 // * feature-gated modules
 #[cfg(feature = "encoding")]
 pub use crate::features::encoding;
@@ -38,8 +42,6 @@ pub use crate::features::encoding;
 pub use crate::features::fs;
 #[cfg(feature = "fsext")]
 pub use crate::features::fsext;
-#[cfg(feature = "parse_time")]
-pub use crate::features::parse_time;
 #[cfg(feature = "ringbuffer")]
 pub use crate::features::ringbuffer;
 #[cfg(feature = "zero-copy")]
diff --git a/src/uucore/src/lib/mods/ranges.rs b/src/uucore/src/lib/mods/ranges.rs
index d4a6bf601..9e1e67d5a 100644
--- a/src/uucore/src/lib/mods/ranges.rs
+++ b/src/uucore/src/lib/mods/ranges.rs
@@ -85,10 +85,9 @@ impl Range {
         let mut ranges: Vec<Range> = vec![];
 
         for item in list.split(',') {
-            match FromStr::from_str(item) {
-                Ok(range_item) => ranges.push(range_item),
-                Err(e) => return Err(format!("range '{}' was invalid: {}", item, e)),
-            }
+            let range_item = FromStr::from_str(item)
+                .map_err(|e| format!("range '{}' was invalid: {}", item, e))?;
+            ranges.push(range_item);
         }
 
         ranges.sort();
diff --git a/src/uucore/src/lib/parser.rs b/src/uucore/src/lib/parser.rs
new file mode 100644
index 000000000..d09777e10
--- /dev/null
+++ b/src/uucore/src/lib/parser.rs
@@ -0,0 +1,2 @@
+pub mod parse_size;
+pub mod parse_time;
diff --git a/src/uucore/src/lib/parser/parse_size.rs b/src/uucore/src/lib/parser/parse_size.rs
new file mode 100644
index 000000000..58213adef
--- /dev/null
+++ b/src/uucore/src/lib/parser/parse_size.rs
@@ -0,0 +1,324 @@
+//  * This file is part of the uutils coreutils package.
+//  *
+//  * For the full copyright and license information, please view the LICENSE
+//  * file that was distributed with this source code.
+
+// spell-checker:ignore (ToDO) hdsf ghead gtail
+
+use std::convert::TryFrom;
+use std::error::Error;
+use std::fmt;
+
+/// Parse a size string into a number of bytes.
+///
+/// A size string comprises an integer and an optional unit. The unit
+/// may be K, M, G, T, P, E, Z or Y (powers of 1024), or KB, MB,
+/// etc. (powers of 1000), or b which is 512.
+/// Binary prefixes can be used, too: KiB=K, MiB=M, and so on.
+///
+/// # Errors
+///
+/// Will return `ParseSizeError` if it’s not possible to parse this
+/// string into a number, e.g. if the string does not begin with a
+/// numeral, or if the unit is not one of the supported units described
+/// in the preceding section.
+///
+/// # Examples
+///
+/// ```rust
+/// use uucore::parse_size::parse_size;
+/// assert_eq!(Ok(123), parse_size("123"));
+/// assert_eq!(Ok(9 * 1000), parse_size("9kB")); // kB is 1000
+/// assert_eq!(Ok(2 * 1024), parse_size("2K")); // K is 1024
+/// ```
+pub fn parse_size(size: &str) -> Result<usize, ParseSizeError> {
+    if size.is_empty() {
+        return Err(ParseSizeError::parse_failure(size));
+    }
+    // Get the numeric part of the size argument. For example, if the
+    // argument is "123K", then the numeric part is "123".
+    let numeric_string: String = size.chars().take_while(|c| c.is_digit(10)).collect();
+    let number: usize = if !numeric_string.is_empty() {
+        match numeric_string.parse() {
+            Ok(n) => n,
+            Err(_) => return Err(ParseSizeError::parse_failure(size)),
+        }
+    } else {
+        1
+    };
+
+    // Get the alphabetic units part of the size argument and compute
+    // the factor it represents. For example, if the argument is "123K",
+    // then the unit part is "K" and the factor is 1024. This may be the
+    // empty string, in which case, the factor is 1.
+    let unit = &size[numeric_string.len()..];
+    let (base, exponent): (u128, u32) = match unit {
+        "" => (1, 0),
+        "b" => (512, 1), // (`od`, `head` and `tail` use "b")
+        "KiB" | "kiB" | "K" | "k" => (1024, 1),
+        "MiB" | "miB" | "M" | "m" => (1024, 2),
+        "GiB" | "giB" | "G" | "g" => (1024, 3),
+        "TiB" | "tiB" | "T" | "t" => (1024, 4),
+        "PiB" | "piB" | "P" | "p" => (1024, 5),
+        "EiB" | "eiB" | "E" | "e" => (1024, 6),
+        "ZiB" | "ziB" | "Z" | "z" => (1024, 7),
+        "YiB" | "yiB" | "Y" | "y" => (1024, 8),
+        "KB" | "kB" => (1000, 1),
+        "MB" | "mB" => (1000, 2),
+        "GB" | "gB" => (1000, 3),
+        "TB" | "tB" => (1000, 4),
+        "PB" | "pB" => (1000, 5),
+        "EB" | "eB" => (1000, 6),
+        "ZB" | "zB" => (1000, 7),
+        "YB" | "yB" => (1000, 8),
+        _ => return Err(ParseSizeError::parse_failure(size)),
+    };
+    let factor = match usize::try_from(base.pow(exponent)) {
+        Ok(n) => n,
+        Err(_) => return Err(ParseSizeError::size_too_big(size)),
+    };
+    number
+        .checked_mul(factor)
+        .ok_or_else(|| ParseSizeError::size_too_big(size))
+}
+
+#[derive(Debug, PartialEq, Eq)]
+pub enum ParseSizeError {
+    ParseFailure(String), // Syntax
+    SizeTooBig(String),   // Overflow
+}
+
+impl Error for ParseSizeError {
+    fn description(&self) -> &str {
+        match *self {
+            ParseSizeError::ParseFailure(ref s) => &*s,
+            ParseSizeError::SizeTooBig(ref s) => &*s,
+        }
+    }
+}
+
+impl fmt::Display for ParseSizeError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        let s = match self {
+            ParseSizeError::ParseFailure(s) => s,
+            ParseSizeError::SizeTooBig(s) => s,
+        };
+        write!(f, "{}", s)
+    }
+}
+
+impl ParseSizeError {
+    fn parse_failure(s: &str) -> ParseSizeError {
+        // stderr on linux (GNU coreutils 8.32)
+        // has to be handled in the respective uutils because strings differ, e.g.:
+        //
+        // `NUM`
+        // head:     invalid number of bytes: ‘1fb’
+        // tail:     invalid number of bytes: ‘1fb’
+        //
+        // `SIZE`
+        // split:    invalid number of bytes: ‘1fb’
+        // truncate: Invalid number: ‘1fb’
+        //
+        // `MODE`
+        // stdbuf:   invalid mode ‘1fb’
+        //
+        // `SIZE`
+        // sort:     invalid suffix in --buffer-size argument '1fb'
+        // sort:     invalid --buffer-size argument 'fb'
+        //
+        // `SIZE`
+        // du:       invalid suffix in --buffer-size argument '1fb'
+        // du:       invalid suffix in --threshold argument '1fb'
+        // du:       invalid --buffer-size argument 'fb'
+        // du:       invalid --threshold argument 'fb'
+        //
+        // `BYTES`
+        // od:       invalid suffix in --read-bytes argument '1fb'
+        // od:       invalid --read-bytes argument  argument 'fb'
+        //                   --skip-bytes
+        //                   --width
+        //                   --strings
+        // etc.
+        ParseSizeError::ParseFailure(format!("‘{}’", s))
+    }
+
+    fn size_too_big(s: &str) -> ParseSizeError {
+        // stderr on linux (GNU coreutils 8.32)
+        // has to be handled in the respective uutils because strings differ, e.g.:
+        //
+        // head:     invalid number of bytes: ‘1Y’: Value too large for defined data type
+        // tail:     invalid number of bytes: ‘1Y’: Value too large for defined data type
+        // split:    invalid number of bytes: ‘1Y’: Value too large for defined data type
+        // truncate:          Invalid number: ‘1Y’: Value too large for defined data type
+        // stdbuf:               invalid mode ‘1Y’: Value too large for defined data type
+        // sort:     -S argument '1Y' too large
+        // du:       -B argument '1Y' too large
+        // od:       -N argument '1Y' too large
+        // etc.
+        //
+        // stderr on macos (brew - GNU coreutils 8.32) also differs for the same version, e.g.:
+        // ghead:   invalid number of bytes: ‘1Y’: Value too large to be stored in data type
+        // gtail:   invalid number of bytes: ‘1Y’: Value too large to be stored in data type
+        ParseSizeError::SizeTooBig(format!("‘{}’: Value too large for defined data type", s))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn variant_eq(a: &ParseSizeError, b: &ParseSizeError) -> bool {
+        std::mem::discriminant(a) == std::mem::discriminant(b)
+    }
+
+    #[test]
+    fn all_suffixes() {
+        // Units  are  K,M,G,T,P,E,Z,Y  (powers  of 1024) or KB,MB,... (powers of 1000).
+        // Binary prefixes can be used, too: KiB=K, MiB=M, and so on.
+        let suffixes = [
+            ('K', 1u32),
+            ('M', 2u32),
+            ('G', 3u32),
+            ('T', 4u32),
+            ('P', 5u32),
+            ('E', 6u32),
+            #[cfg(target_pointer_width = "128")]
+            ('Z', 7u32), // ParseSizeError::SizeTooBig on x64
+            #[cfg(target_pointer_width = "128")]
+            ('Y', 8u32), // ParseSizeError::SizeTooBig on x64
+        ];
+
+        for &(c, exp) in &suffixes {
+            let s = format!("2{}B", c); // KB
+            assert_eq!(Ok((2 * (1000_u128).pow(exp)) as usize), parse_size(&s));
+            let s = format!("2{}", c); // K
+            assert_eq!(Ok((2 * (1024_u128).pow(exp)) as usize), parse_size(&s));
+            let s = format!("2{}iB", c); // KiB
+            assert_eq!(Ok((2 * (1024_u128).pow(exp)) as usize), parse_size(&s));
+            let s = format!("2{}iB", c.to_lowercase()); // kiB
+            assert_eq!(Ok((2 * (1024_u128).pow(exp)) as usize), parse_size(&s));
+
+            // suffix only
+            let s = format!("{}B", c); // KB
+            assert_eq!(Ok(((1000_u128).pow(exp)) as usize), parse_size(&s));
+            let s = format!("{}", c); // K
+            assert_eq!(Ok(((1024_u128).pow(exp)) as usize), parse_size(&s));
+            let s = format!("{}iB", c); // KiB
+            assert_eq!(Ok(((1024_u128).pow(exp)) as usize), parse_size(&s));
+            let s = format!("{}iB", c.to_lowercase()); // kiB
+            assert_eq!(Ok(((1024_u128).pow(exp)) as usize), parse_size(&s));
+        }
+    }
+
+    #[test]
+    #[cfg(not(target_pointer_width = "128"))]
+    fn overflow_x64() {
+        assert!(parse_size("10000000000000000000000").is_err());
+        assert!(parse_size("1000000000T").is_err());
+        assert!(parse_size("100000P").is_err());
+        assert!(parse_size("100E").is_err());
+        assert!(parse_size("1Z").is_err());
+        assert!(parse_size("1Y").is_err());
+
+        assert!(variant_eq(
+            &parse_size("1Z").unwrap_err(),
+            &ParseSizeError::SizeTooBig(String::new())
+        ));
+
+        assert_eq!(
+            ParseSizeError::SizeTooBig("‘1Y’: Value too large for defined data type".to_string()),
+            parse_size("1Y").unwrap_err()
+        );
+    }
+
+    #[test]
+    #[cfg(target_pointer_width = "32")]
+    fn overflow_x32() {
+        assert!(variant_eq(
+            &parse_size("1T").unwrap_err(),
+            &ParseSizeError::SizeTooBig(String::new())
+        ));
+        assert!(variant_eq(
+            &parse_size("1000G").unwrap_err(),
+            &ParseSizeError::SizeTooBig(String::new())
+        ));
+    }
+
+    #[test]
+    fn invalid_syntax() {
+        let test_strings = [
+            "328hdsf3290",
+            "5MiB nonsense",
+            "5mib",
+            "biB",
+            "-",
+            "+",
+            "",
+            "-1",
+            "1e2",
+            "∞",
+        ];
+        for &test_string in &test_strings {
+            assert_eq!(
+                parse_size(test_string).unwrap_err(),
+                ParseSizeError::ParseFailure(format!("‘{}’", test_string))
+            );
+        }
+    }
+
+    #[test]
+    fn b_suffix() {
+        assert_eq!(Ok(3 * 512), parse_size("3b")); // b is 512
+    }
+
+    #[test]
+    fn no_suffix() {
+        assert_eq!(Ok(1234), parse_size("1234"));
+        assert_eq!(Ok(0), parse_size("0"));
+        assert_eq!(Ok(5), parse_size("5"));
+        assert_eq!(Ok(999), parse_size("999"));
+    }
+
+    #[test]
+    fn kilobytes_suffix() {
+        assert_eq!(Ok(123 * 1000), parse_size("123KB")); // KB is 1000
+        assert_eq!(Ok(9 * 1000), parse_size("9kB")); // kB is 1000
+        assert_eq!(Ok(2 * 1024), parse_size("2K")); // K is 1024
+        assert_eq!(Ok(0), parse_size("0K"));
+        assert_eq!(Ok(0), parse_size("0KB"));
+        assert_eq!(Ok(1000), parse_size("KB"));
+        assert_eq!(Ok(1024), parse_size("K"));
+        assert_eq!(Ok(2000), parse_size("2kB"));
+        assert_eq!(Ok(4000), parse_size("4KB"));
+    }
+
+    #[test]
+    fn megabytes_suffix() {
+        assert_eq!(Ok(123 * 1024 * 1024), parse_size("123M"));
+        assert_eq!(Ok(123 * 1000 * 1000), parse_size("123MB"));
+        assert_eq!(Ok(1024 * 1024), parse_size("M"));
+        assert_eq!(Ok(1000 * 1000), parse_size("MB"));
+        assert_eq!(Ok(2 * 1_048_576), parse_size("2m"));
+        assert_eq!(Ok(4 * 1_048_576), parse_size("4M"));
+        assert_eq!(Ok(2_000_000), parse_size("2mB"));
+        assert_eq!(Ok(4_000_000), parse_size("4MB"));
+    }
+
+    #[test]
+    fn gigabytes_suffix() {
+        assert_eq!(Ok(1_073_741_824), parse_size("1G"));
+        assert_eq!(Ok(2_000_000_000), parse_size("2GB"));
+    }
+
+    #[test]
+    #[cfg(target_pointer_width = "64")]
+    fn x64() {
+        assert_eq!(Ok(1_099_511_627_776), parse_size("1T"));
+        assert_eq!(Ok(1_125_899_906_842_624), parse_size("1P"));
+        assert_eq!(Ok(1_152_921_504_606_846_976), parse_size("1E"));
+        assert_eq!(Ok(2_000_000_000_000), parse_size("2TB"));
+        assert_eq!(Ok(2_000_000_000_000_000), parse_size("2PB"));
+        assert_eq!(Ok(2_000_000_000_000_000_000), parse_size("2EB"));
+    }
+}
diff --git a/src/uucore/src/lib/features/parse_time.rs b/src/uucore/src/lib/parser/parse_time.rs
similarity index 78%
rename from src/uucore/src/lib/features/parse_time.rs
rename to src/uucore/src/lib/parser/parse_time.rs
index 8e822685b..fdf43b727 100644
--- a/src/uucore/src/lib/features/parse_time.rs
+++ b/src/uucore/src/lib/parser/parse_time.rs
@@ -20,20 +20,18 @@ pub fn from_str(string: &str) -> Result<Duration, String> {
         'm' | 'M' => (slice, 60),
         'h' | 'H' => (slice, 60 * 60),
         'd' | 'D' => (slice, 60 * 60 * 24),
-        val => {
-            if !val.is_alphabetic() {
-                (string, 1)
-            } else if string == "inf" || string == "infinity" {
+        val if !val.is_alphabetic() => (string, 1),
+        _ => {
+            if string == "inf" || string == "infinity" {
                 ("inf", 1)
             } else {
                 return Err(format!("invalid time interval '{}'", string));
             }
         }
     };
-    let num = match numstr.parse::<f64>() {
-        Ok(m) => m,
-        Err(e) => return Err(format!("invalid time interval '{}': {}", string, e)),
-    };
+    let num = numstr
+        .parse::<f64>()
+        .map_err(|e| format!("invalid time interval '{}': {}", string, e))?;
 
     const NANOS_PER_SEC: u32 = 1_000_000_000;
     let whole_secs = num.trunc();
diff --git a/tests/by-util/test_cat.rs b/tests/by-util/test_cat.rs
index fadf378ab..d83b5515b 100644
--- a/tests/by-util/test_cat.rs
+++ b/tests/by-util/test_cat.rs
@@ -438,7 +438,7 @@ fn test_domain_socket() {
     let child = new_ucmd!().args(&[socket_path]).run_no_wait();
     barrier.wait();
     let stdout = &child.wait_with_output().unwrap().stdout;
-    let output = String::from_utf8_lossy(&stdout);
+    let output = String::from_utf8_lossy(stdout);
     assert_eq!("a\tb", output);
 
     thread.join().unwrap();
diff --git a/tests/by-util/test_chgrp.rs b/tests/by-util/test_chgrp.rs
index 45380b80b..762e922c4 100644
--- a/tests/by-util/test_chgrp.rs
+++ b/tests/by-util/test_chgrp.rs
@@ -1,4 +1,4 @@
-// spell-checker:ignore (words) nosuchgroup
+// spell-checker:ignore (words) nosuchgroup groupname
 
 use crate::common::util::*;
 use rust_users::*;
@@ -10,6 +10,33 @@ fn test_invalid_option() {
 
 static DIR: &str = "/tmp";
 
+// we should always get both arguments, regardless of whether --reference was used
+#[test]
+fn test_help() {
+    new_ucmd!()
+        .arg("--help")
+        .succeeds()
+        .stdout_contains("ARGS:\n    <GROUP>      \n    <FILE>...    ");
+}
+
+#[test]
+fn test_help_ref() {
+    new_ucmd!()
+        .arg("--help")
+        .arg("--reference=ref_file")
+        .succeeds()
+        .stdout_contains("ARGS:\n    <GROUP>      \n    <FILE>...    ");
+}
+
+#[test]
+fn test_ref_help() {
+    new_ucmd!()
+        .arg("--reference=ref_file")
+        .arg("--help")
+        .succeeds()
+        .stdout_contains("ARGS:\n    <GROUP>      \n    <FILE>...    ");
+}
+
 #[test]
 fn test_invalid_group() {
     new_ucmd!()
@@ -121,9 +148,52 @@ fn test_reference() {
 fn test_reference() {
     new_ucmd!()
         .arg("-v")
-        .arg("--reference=/etc/passwd")
+        .arg("--reference=ref_file")
         .arg("/etc")
-        .succeeds();
+        .fails()
+        // group name can differ, so just check the first part of the message
+        .stderr_contains("chgrp: changing group of '/etc': Operation not permitted (os error 1)\nfailed to change group of '/etc' from ");
+}
+
+#[test]
+#[cfg(any(target_os = "linux", target_vendor = "apple"))]
+fn test_reference_multi_no_equal() {
+    new_ucmd!()
+        .arg("-v")
+        .arg("--reference")
+        .arg("ref_file")
+        .arg("file1")
+        .arg("file2")
+        .succeeds()
+        .stderr_contains("chgrp: group of 'file1' retained as ")
+        .stderr_contains("\nchgrp: group of 'file2' retained as ");
+}
+
+#[test]
+#[cfg(any(target_os = "linux", target_vendor = "apple"))]
+fn test_reference_last() {
+    new_ucmd!()
+        .arg("-v")
+        .arg("file1")
+        .arg("file2")
+        .arg("file3")
+        .arg("--reference")
+        .arg("ref_file")
+        .succeeds()
+        .stderr_contains("chgrp: group of 'file1' retained as ")
+        .stderr_contains("\nchgrp: group of 'file2' retained as ")
+        .stderr_contains("\nchgrp: group of 'file3' retained as ");
+}
+
+#[test]
+fn test_missing_files() {
+    new_ucmd!()
+        .arg("-v")
+        .arg("groupname")
+        .fails()
+        .stderr_contains(
+            "error: The following required arguments were not provided:\n    <FILE>...\n",
+        );
 }
 
 #[test]
@@ -135,7 +205,7 @@ fn test_big_p() {
             .arg("bin")
             .arg("/proc/self/cwd")
             .fails()
-            .stderr_is(
+            .stderr_contains(
                 "chgrp: changing group of '/proc/self/cwd': Operation not permitted (os error 1)\n",
             );
     }
diff --git a/tests/by-util/test_cp.rs b/tests/by-util/test_cp.rs
index ff607f984..bc6c6fc79 100644
--- a/tests/by-util/test_cp.rs
+++ b/tests/by-util/test_cp.rs
@@ -618,7 +618,7 @@ fn test_cp_deref() {
     // Check the content of the destination file that was copied.
     assert_eq!(at.read(TEST_COPY_TO_FOLDER_FILE), "Hello, World!\n");
     let path_to_check = path_to_new_symlink.to_str().unwrap();
-    assert_eq!(at.read(&path_to_check), "Hello, World!\n");
+    assert_eq!(at.read(path_to_check), "Hello, World!\n");
 }
 #[test]
 fn test_cp_no_deref() {
@@ -655,7 +655,7 @@ fn test_cp_no_deref() {
     // Check the content of the destination file that was copied.
     assert_eq!(at.read(TEST_COPY_TO_FOLDER_FILE), "Hello, World!\n");
     let path_to_check = path_to_new_symlink.to_str().unwrap();
-    assert_eq!(at.read(&path_to_check), "Hello, World!\n");
+    assert_eq!(at.read(path_to_check), "Hello, World!\n");
 }
 
 #[test]
@@ -823,7 +823,7 @@ fn test_cp_deref_folder_to_folder() {
 
     // Check the content of the symlink
     let path_to_check = path_to_new_symlink.to_str().unwrap();
-    assert_eq!(at.read(&path_to_check), "Hello, World!\n");
+    assert_eq!(at.read(path_to_check), "Hello, World!\n");
 }
 
 #[test]
@@ -923,7 +923,7 @@ fn test_cp_no_deref_folder_to_folder() {
 
     // Check the content of the symlink
     let path_to_check = path_to_new_symlink.to_str().unwrap();
-    assert_eq!(at.read(&path_to_check), "Hello, World!\n");
+    assert_eq!(at.read(path_to_check), "Hello, World!\n");
 }
 
 #[test]
diff --git a/tests/by-util/test_du.rs b/tests/by-util/test_du.rs
index 3c177c6bf..8d1267423 100644
--- a/tests/by-util/test_du.rs
+++ b/tests/by-util/test_du.rs
@@ -1,3 +1,8 @@
+//  * This file is part of the uutils coreutils package.
+//  *
+//  * For the full copyright and license information, please view the LICENSE
+//  * file that was distributed with this source code.
+
 // spell-checker:ignore (paths) sublink subwords
 
 use crate::common::util::*;
@@ -73,6 +78,23 @@ fn _du_basics_subdir(s: &str) {
     }
 }
 
+#[test]
+fn test_du_invalid_size() {
+    new_ucmd!()
+        .arg("--block-size=1fb4t")
+        .arg("/tmp")
+        .fails()
+        .code_is(1)
+        .stderr_only("du: invalid --block-size argument '1fb4t'");
+    #[cfg(not(target_pointer_width = "128"))]
+    new_ucmd!()
+        .arg("--block-size=1Y")
+        .arg("/tmp")
+        .fails()
+        .code_is(1)
+        .stderr_only("du: --block-size argument '1Y' too large");
+}
+
 #[test]
 fn test_du_basics_bad_name() {
     new_ucmd!()
@@ -312,3 +334,20 @@ fn _du_no_permission(s: &str) {
 fn _du_no_permission(s: &str) {
     assert_eq!(s, "4\tsubdir/links\n");
 }
+
+#[test]
+fn test_du_one_file_system() {
+    let scene = TestScenario::new(util_name!());
+
+    let result = scene.ucmd().arg("-x").arg(SUB_DIR).succeeds();
+
+    #[cfg(target_os = "linux")]
+    {
+        let result_reference = scene.cmd("du").arg("-x").arg(SUB_DIR).run();
+        if result_reference.succeeded() {
+            assert_eq!(result.stdout_str(), result_reference.stdout_str());
+            return;
+        }
+    }
+    _du_basics_subdir(result.stdout_str());
+}
diff --git a/tests/by-util/test_env.rs b/tests/by-util/test_env.rs
index 4db3b59bd..1d76c433d 100644
--- a/tests/by-util/test_env.rs
+++ b/tests/by-util/test_env.rs
@@ -187,11 +187,10 @@ fn test_change_directory() {
         .arg(&temporary_path)
         .succeeds()
         .stdout_move_str();
-    assert_eq!(
-        out.lines()
-            .any(|line| line.ends_with(temporary_path.file_name().unwrap().to_str().unwrap())),
-        false
-    );
+
+    assert!(!out
+        .lines()
+        .any(|line| line.ends_with(temporary_path.file_name().unwrap().to_str().unwrap())));
 }
 
 #[test]
diff --git a/tests/by-util/test_groups.rs b/tests/by-util/test_groups.rs
index 26ab6a75a..c1b98aea1 100644
--- a/tests/by-util/test_groups.rs
+++ b/tests/by-util/test_groups.rs
@@ -1,7 +1,7 @@
 use crate::common::util::*;
 
 #[test]
-#[cfg(any(target_vendor = "apple", target_os = "linux"))]
+#[cfg(unix)]
 fn test_groups() {
     if !is_ci() {
         new_ucmd!().succeeds().stdout_is(expected_result(&[]));
@@ -13,7 +13,7 @@ fn test_groups() {
 }
 
 #[test]
-#[cfg(any(target_os = "linux"))]
+#[cfg(unix)]
 #[ignore = "fixme: 'groups USERNAME' needs more debugging"]
 fn test_groups_username() {
     let scene = TestScenario::new(util_name!());
@@ -37,17 +37,20 @@ fn test_groups_username() {
         .stdout_is(expected_result(&[&username]));
 }
 
-#[cfg(any(target_vendor = "apple", target_os = "linux"))]
+#[cfg(unix)]
 fn expected_result(args: &[&str]) -> String {
-    #[cfg(target_os = "linux")]
-    let util_name = util_name!();
-    #[cfg(target_vendor = "apple")]
-    let util_name = format!("g{}", util_name!());
+    // We want to use GNU id. On most linux systems, this is "id", but on
+    // bsd-like systems (e.g. FreeBSD, MacOS), it is commonly "gid".
+    #[cfg(any(target_os = "linux"))]
+    let util_name = "id";
+    #[cfg(not(target_os = "linux"))]
+    let util_name = "gid";
 
-    TestScenario::new(&util_name)
+    TestScenario::new(util_name)
         .cmd_keepenv(util_name)
         .env("LANGUAGE", "C")
         .args(args)
+        .args(&["-Gn"])
         .succeeds()
         .stdout_move_str()
 }
diff --git a/tests/by-util/test_head.rs b/tests/by-util/test_head.rs
index 7daa80e3a..2c4b66696 100755
--- a/tests/by-util/test_head.rs
+++ b/tests/by-util/test_head.rs
@@ -1,4 +1,9 @@
-// spell-checker:ignore (words) bogusfile emptyfile
+//  * This file is part of the uutils coreutils package.
+//  *
+//  * For the full copyright and license information, please view the LICENSE
+//  * file that was distributed with this source code.
+
+// spell-checker:ignore (words) bogusfile emptyfile abcdefghijklmnopqrstuvwxyz abcdefghijklmnopqrstu
 
 use crate::common::util::*;
 
@@ -244,3 +249,61 @@ hello
 ",
         );
 }
+
+#[test]
+fn test_head_invalid_num() {
+    new_ucmd!()
+        .args(&["-c", "1024R", "emptyfile.txt"])
+        .fails()
+        .stderr_is("head: invalid number of bytes: ‘1024R’");
+    new_ucmd!()
+        .args(&["-n", "1024R", "emptyfile.txt"])
+        .fails()
+        .stderr_is("head: invalid number of lines: ‘1024R’");
+    #[cfg(not(target_pointer_width = "128"))]
+    new_ucmd!()
+        .args(&["-c", "1Y", "emptyfile.txt"])
+        .fails()
+        .stderr_is("head: invalid number of bytes: ‘1Y’: Value too large for defined data type");
+    #[cfg(not(target_pointer_width = "128"))]
+    new_ucmd!()
+        .args(&["-n", "1Y", "emptyfile.txt"])
+        .fails()
+        .stderr_is("head: invalid number of lines: ‘1Y’: Value too large for defined data type");
+    #[cfg(target_pointer_width = "32")]
+    {
+        let sizes = ["1000G", "10T"];
+        for size in &sizes {
+            new_ucmd!()
+                .args(&["-c", size])
+                .fails()
+                .code_is(1)
+                .stderr_only(format!(
+                    "head: invalid number of bytes: ‘{}’: Value too large for defined data type",
+                    size
+                ));
+        }
+    }
+}
+
+#[test]
+fn test_head_num_with_undocumented_sign_bytes() {
+    // tail: '-' is not documented (8.32 man pages)
+    // head: '+' is not documented (8.32 man pages)
+    const ALPHABET: &str = "abcdefghijklmnopqrstuvwxyz";
+    new_ucmd!()
+        .args(&["-c", "5"])
+        .pipe_in(ALPHABET)
+        .succeeds()
+        .stdout_is("abcde");
+    new_ucmd!()
+        .args(&["-c", "-5"])
+        .pipe_in(ALPHABET)
+        .succeeds()
+        .stdout_is("abcdefghijklmnopqrstu");
+    new_ucmd!()
+        .args(&["-c", "+5"])
+        .pipe_in(ALPHABET)
+        .succeeds()
+        .stdout_is("abcde");
+}
diff --git a/tests/by-util/test_ln.rs b/tests/by-util/test_ln.rs
index e475e3608..fc97ff779 100644
--- a/tests/by-util/test_ln.rs
+++ b/tests/by-util/test_ln.rs
@@ -428,20 +428,6 @@ fn test_symlink_relative() {
     assert_eq!(at.resolve_link(link), file_a);
 }
 
-#[test]
-fn test_hardlink_relative() {
-    let (at, mut ucmd) = at_and_ucmd!();
-    let file_a = "test_hardlink_relative_a";
-    let link = "test_hardlink_relative_link";
-
-    at.touch(file_a);
-
-    // relative hardlink
-    ucmd.args(&["-r", "-v", file_a, link])
-        .succeeds()
-        .stdout_only(format!("'{}' -> '{}'\n", link, file_a));
-}
-
 #[test]
 fn test_symlink_relative_path() {
     let (at, mut ucmd) = at_and_ucmd!();
@@ -571,3 +557,26 @@ fn test_symlink_no_deref_file() {
     assert!(at.is_symlink(link));
     assert_eq!(at.resolve_link(link), file1);
 }
+
+#[test]
+fn test_relative_requires_symbolic() {
+    new_ucmd!().args(&["-r", "foo", "bar"]).fails();
+}
+
+#[test]
+fn test_relative_dst_already_symlink() {
+    let (at, mut ucmd) = at_and_ucmd!();
+    at.touch("file1");
+    at.symlink_file("file1", "file2");
+    ucmd.arg("-srf").arg("file1").arg("file2").succeeds();
+    at.is_symlink("file2");
+}
+
+#[test]
+fn test_relative_src_already_symlink() {
+    let (at, mut ucmd) = at_and_ucmd!();
+    at.touch("file1");
+    at.symlink_file("file1", "file2");
+    ucmd.arg("-sr").arg("file2").arg("file3").succeeds();
+    assert!(at.resolve_link("file3").ends_with("file1"));
+}
diff --git a/tests/by-util/test_ls.rs b/tests/by-util/test_ls.rs
index 20c6b913d..f8aa4453b 100644
--- a/tests/by-util/test_ls.rs
+++ b/tests/by-util/test_ls.rs
@@ -398,7 +398,7 @@ fn test_ls_long_formats() {
         .arg("--author")
         .arg("test-long-formats")
         .succeeds();
-    assert!(re_three.is_match(&result.stdout_str()));
+    assert!(re_three.is_match(result.stdout_str()));
 
     #[cfg(unix)]
     {
@@ -701,20 +701,20 @@ fn test_ls_styles() {
         .arg("-l")
         .arg("--time-style=full-iso")
         .succeeds();
-    assert!(re_full.is_match(&result.stdout_str()));
+    assert!(re_full.is_match(result.stdout_str()));
     //long-iso
     let result = scene
         .ucmd()
         .arg("-l")
         .arg("--time-style=long-iso")
         .succeeds();
-    assert!(re_long.is_match(&result.stdout_str()));
+    assert!(re_long.is_match(result.stdout_str()));
     //iso
     let result = scene.ucmd().arg("-l").arg("--time-style=iso").succeeds();
-    assert!(re_iso.is_match(&result.stdout_str()));
+    assert!(re_iso.is_match(result.stdout_str()));
     //locale
     let result = scene.ucmd().arg("-l").arg("--time-style=locale").succeeds();
-    assert!(re_locale.is_match(&result.stdout_str()));
+    assert!(re_locale.is_match(result.stdout_str()));
 
     //Overwrite options tests
     let result = scene
@@ -723,19 +723,19 @@ fn test_ls_styles() {
         .arg("--time-style=long-iso")
         .arg("--time-style=iso")
         .succeeds();
-    assert!(re_iso.is_match(&result.stdout_str()));
+    assert!(re_iso.is_match(result.stdout_str()));
     let result = scene
         .ucmd()
         .arg("--time-style=iso")
         .arg("--full-time")
         .succeeds();
-    assert!(re_full.is_match(&result.stdout_str()));
+    assert!(re_full.is_match(result.stdout_str()));
     let result = scene
         .ucmd()
         .arg("--full-time")
         .arg("--time-style=iso")
         .succeeds();
-    assert!(re_iso.is_match(&result.stdout_str()));
+    assert!(re_iso.is_match(result.stdout_str()));
 
     let result = scene
         .ucmd()
@@ -743,7 +743,7 @@ fn test_ls_styles() {
         .arg("--time-style=iso")
         .arg("--full-time")
         .succeeds();
-    assert!(re_full.is_match(&result.stdout_str()));
+    assert!(re_full.is_match(result.stdout_str()));
 
     let result = scene
         .ucmd()
@@ -751,7 +751,7 @@ fn test_ls_styles() {
         .arg("-x")
         .arg("-l")
         .succeeds();
-    assert!(re_full.is_match(&result.stdout_str()));
+    assert!(re_full.is_match(result.stdout_str()));
 
     at.touch("test2");
     let result = scene.ucmd().arg("--full-time").arg("-x").succeeds();
@@ -1143,7 +1143,7 @@ fn test_ls_indicator_style() {
     for opt in options {
         scene
             .ucmd()
-            .arg(format!("{}", opt))
+            .arg(opt.to_string())
             .succeeds()
             .stdout_contains(&"/");
     }
diff --git a/tests/by-util/test_od.rs b/tests/by-util/test_od.rs
index c21c683dc..33d7d4dc4 100644
--- a/tests/by-util/test_od.rs
+++ b/tests/by-util/test_od.rs
@@ -1,3 +1,8 @@
+//  * This file is part of the uutils coreutils package.
+//  *
+//  * For the full copyright and license information, please view the LICENSE
+//  * file that was distributed with this source code.
+
 extern crate unindent;
 
 use self::unindent::*;
@@ -804,3 +809,40 @@ fn test_traditional_only_label() {
             ",
         ));
 }
+
+#[test]
+fn test_od_invalid_bytes() {
+    const INVALID_SIZE: &str = "1fb4t";
+    const BIG_SIZE: &str = "1Y";
+
+    // NOTE:
+    // GNU's od (8.32) with option '--width' does not accept 'Y' as valid suffix.
+    // According to the man page it should be valid in the same way it is valid for
+    // '--read-bytes' and '--skip-bytes'.
+
+    let options = [
+        "--read-bytes",
+        "--skip-bytes",
+        "--width",
+        // "--strings", // TODO: consider testing here once '--strings' is implemented
+    ];
+    for option in &options {
+        new_ucmd!()
+            .arg(format!("{}={}", option, INVALID_SIZE))
+            .arg("file")
+            .fails()
+            .code_is(1)
+            .stderr_only(format!(
+                "od: invalid {} argument '{}'",
+                option, INVALID_SIZE
+            ));
+
+        #[cfg(not(target_pointer_width = "128"))]
+        new_ucmd!()
+            .arg(format!("{}={}", option, BIG_SIZE))
+            .arg("file")
+            .fails()
+            .code_is(1)
+            .stderr_only(format!("od: {} argument '{}' too large", option, BIG_SIZE));
+    }
+}
diff --git a/tests/by-util/test_pathchk.rs b/tests/by-util/test_pathchk.rs
index 3bc12f0b6..8ba3b9033 100644
--- a/tests/by-util/test_pathchk.rs
+++ b/tests/by-util/test_pathchk.rs
@@ -38,7 +38,7 @@ fn test_posix_mode() {
 
     // fail on long path
     new_ucmd!()
-        .args(&["-p", &"dir".repeat(libc::PATH_MAX as usize + 1).as_str()])
+        .args(&["-p", "dir".repeat(libc::PATH_MAX as usize + 1).as_str()])
         .fails()
         .no_stdout();
 
@@ -46,7 +46,7 @@ fn test_posix_mode() {
     new_ucmd!()
         .args(&[
             "-p",
-            &format!("dir/{}", "file".repeat(libc::FILENAME_MAX as usize + 1)).as_str(),
+            format!("dir/{}", "file".repeat(libc::FILENAME_MAX as usize + 1)).as_str(),
         ])
         .fails()
         .no_stdout();
@@ -76,7 +76,7 @@ fn test_posix_special() {
 
     // fail on long path
     new_ucmd!()
-        .args(&["-P", &"dir".repeat(libc::PATH_MAX as usize + 1).as_str()])
+        .args(&["-P", "dir".repeat(libc::PATH_MAX as usize + 1).as_str()])
         .fails()
         .no_stdout();
 
@@ -84,7 +84,7 @@ fn test_posix_special() {
     new_ucmd!()
         .args(&[
             "-P",
-            &format!("dir/{}", "file".repeat(libc::FILENAME_MAX as usize + 1)).as_str(),
+            format!("dir/{}", "file".repeat(libc::FILENAME_MAX as usize + 1)).as_str(),
         ])
         .fails()
         .no_stdout();
@@ -117,7 +117,7 @@ fn test_posix_all() {
         .args(&[
             "-p",
             "-P",
-            &"dir".repeat(libc::PATH_MAX as usize + 1).as_str(),
+            "dir".repeat(libc::PATH_MAX as usize + 1).as_str(),
         ])
         .fails()
         .no_stdout();
@@ -127,7 +127,7 @@ fn test_posix_all() {
         .args(&[
             "-p",
             "-P",
-            &format!("dir/{}", "file".repeat(libc::FILENAME_MAX as usize + 1)).as_str(),
+            format!("dir/{}", "file".repeat(libc::FILENAME_MAX as usize + 1)).as_str(),
         ])
         .fails()
         .no_stdout();
diff --git a/tests/by-util/test_pinky.rs b/tests/by-util/test_pinky.rs
index 0813e5e1b..8b50ec2bd 100644
--- a/tests/by-util/test_pinky.rs
+++ b/tests/by-util/test_pinky.rs
@@ -102,6 +102,8 @@ fn expected_result(args: &[&str]) -> String {
     #[cfg(target_vendor = "apple")]
     let util_name = format!("g{}", util_name!());
 
+    // note: clippy::needless_borrow *false positive*
+    #[allow(clippy::needless_borrow)]
     TestScenario::new(&util_name)
         .cmd_keepenv(util_name)
         .env("LANGUAGE", "C")
diff --git a/tests/by-util/test_sort.rs b/tests/by-util/test_sort.rs
index 75611abfc..2894d3007 100644
--- a/tests/by-util/test_sort.rs
+++ b/tests/by-util/test_sort.rs
@@ -1,3 +1,8 @@
+//  * This file is part of the uutils coreutils package.
+//  *
+//  * For the full copyright and license information, please view the LICENSE
+//  * file that was distributed with this source code.
+
 // spell-checker:ignore (words) ints
 
 use crate::common::util::*;
@@ -21,9 +26,7 @@ fn test_helper(file_name: &str, possible_args: &[&str]) {
 
 #[test]
 fn test_buffer_sizes() {
-    let buffer_sizes = [
-        "0", "50K", "50k", "1M", "100M", "1000G", "10T", "500E", "1Y",
-    ];
+    let buffer_sizes = ["0", "50K", "50k", "1M", "100M"];
     for buffer_size in &buffer_sizes {
         new_ucmd!()
             .arg("-n")
@@ -32,6 +35,20 @@ fn test_buffer_sizes() {
             .arg("ext_sort.txt")
             .succeeds()
             .stdout_is_fixture("ext_sort.expected");
+
+        #[cfg(not(target_pointer_width = "32"))]
+        {
+            let buffer_sizes = ["1000G", "10T"];
+            for buffer_size in &buffer_sizes {
+                new_ucmd!()
+                    .arg("-n")
+                    .arg("-S")
+                    .arg(buffer_size)
+                    .arg("ext_sort.txt")
+                    .succeeds()
+                    .stdout_is_fixture("ext_sort.expected");
+            }
+        }
     }
 }
 
@@ -43,11 +60,39 @@ fn test_invalid_buffer_size() {
             .arg("-S")
             .arg(invalid_buffer_size)
             .fails()
+            .code_is(2)
             .stderr_only(format!(
-                "sort: failed to parse buffer size `{}`: invalid digit found in string",
+                "sort: invalid --buffer-size argument '{}'",
                 invalid_buffer_size
             ));
     }
+    #[cfg(not(target_pointer_width = "128"))]
+    new_ucmd!()
+        .arg("-n")
+        .arg("-S")
+        .arg("1Y")
+        .arg("ext_sort.txt")
+        .fails()
+        .code_is(2)
+        .stderr_only("sort: --buffer-size argument '1Y' too large");
+
+    #[cfg(target_pointer_width = "32")]
+    {
+        let buffer_sizes = ["1000G", "10T"];
+        for buffer_size in &buffer_sizes {
+            new_ucmd!()
+                .arg("-n")
+                .arg("-S")
+                .arg(buffer_size)
+                .arg("ext_sort.txt")
+                .fails()
+                .code_is(2)
+                .stderr_only(format!(
+                    "sort: --buffer-size argument '{}' too large",
+                    buffer_size
+                ));
+        }
+    }
 }
 
 #[test]
@@ -804,7 +849,7 @@ fn sort_multiple() {
 #[test]
 fn sort_empty_chunk() {
     new_ucmd!()
-        .args(&["-S", "40B"])
+        .args(&["-S", "40b"])
         .pipe_in("a\na\n")
         .succeeds()
         .stdout_is("a\na\n");
@@ -844,12 +889,7 @@ fn test_compress_fail() {
 #[test]
 fn test_merge_batches() {
     new_ucmd!()
-        .args(&[
-            "ext_sort.txt",
-            "-n",
-            "-S",
-            "150B",
-        ])
+        .args(&["ext_sort.txt", "-n", "-S", "150b"])
         .succeeds()
         .stdout_only_fixture("ext_sort.expected");
 }
diff --git a/tests/by-util/test_split.rs b/tests/by-util/test_split.rs
index 85b28326b..a1350534f 100644
--- a/tests/by-util/test_split.rs
+++ b/tests/by-util/test_split.rs
@@ -1,3 +1,8 @@
+//  * This file is part of the uutils coreutils package.
+//  *
+//  * For the full copyright and license information, please view the LICENSE
+//  * file that was distributed with this source code.
+
 extern crate rand;
 extern crate regex;
 
@@ -285,3 +290,53 @@ fn test_filter_command_fails() {
     ucmd.args(&["--filter=/a/path/that/totally/does/not/exist", name])
         .fails();
 }
+
+#[test]
+fn test_split_lines_number() {
+    // Test if stdout/stderr for '--lines' option is correct
+    let scene = TestScenario::new(util_name!());
+    let at = &scene.fixtures;
+    at.touch("file");
+
+    scene
+        .ucmd()
+        .args(&["--lines", "2", "file"])
+        .succeeds()
+        .no_stderr()
+        .no_stdout();
+    scene
+        .ucmd()
+        .args(&["--lines", "2fb", "file"])
+        .fails()
+        .code_is(1)
+        .stderr_only("split: invalid number of lines: ‘2fb’");
+}
+
+#[test]
+fn test_split_invalid_bytes_size() {
+    new_ucmd!()
+        .args(&["-b", "1024R"])
+        .fails()
+        .code_is(1)
+        .stderr_only("split: invalid number of bytes: ‘1024R’");
+    #[cfg(not(target_pointer_width = "128"))]
+    new_ucmd!()
+        .args(&["-b", "1Y"])
+        .fails()
+        .code_is(1)
+        .stderr_only("split: invalid number of bytes: ‘1Y’: Value too large for defined data type");
+    #[cfg(target_pointer_width = "32")]
+    {
+        let sizes = ["1000G", "10T"];
+        for size in &sizes {
+            new_ucmd!()
+                .args(&["-b", size])
+                .fails()
+                .code_is(1)
+                .stderr_only(format!(
+                    "split: invalid number of bytes: ‘{}’: Value too large for defined data type",
+                    size
+                ));
+        }
+    }
+}
diff --git a/tests/by-util/test_stat.rs b/tests/by-util/test_stat.rs
index 89dd96752..37328d5ae 100644
--- a/tests/by-util/test_stat.rs
+++ b/tests/by-util/test_stat.rs
@@ -313,6 +313,8 @@ fn expected_result(args: &[&str]) -> String {
     #[cfg(target_vendor = "apple")]
     let util_name = format!("g{}", util_name!());
 
+    // note: clippy::needless_borrow *false positive*
+    #[allow(clippy::needless_borrow)]
     TestScenario::new(&util_name)
         .cmd_keepenv(util_name)
         .env("LANGUAGE", "C")
diff --git a/tests/by-util/test_stdbuf.rs b/tests/by-util/test_stdbuf.rs
index 2e09601ce..fc1b9324a 100644
--- a/tests/by-util/test_stdbuf.rs
+++ b/tests/by-util/test_stdbuf.rs
@@ -57,8 +57,18 @@ fn test_stdbuf_line_buffering_stdin_fails() {
 #[cfg(not(target_os = "windows"))]
 #[test]
 fn test_stdbuf_invalid_mode_fails() {
-    new_ucmd!()
-        .args(&["-i", "1024R", "head"])
-        .fails()
-        .stderr_is("stdbuf: invalid mode 1024R\nTry 'stdbuf --help' for more information.");
+    let options = ["--input", "--output", "--error"];
+    for option in &options {
+        new_ucmd!()
+            .args(&[*option, "1024R", "head"])
+            .fails()
+            .code_is(125)
+            .stderr_only("stdbuf: invalid mode ‘1024R’");
+        #[cfg(not(target_pointer_width = "128"))]
+        new_ucmd!()
+            .args(&[*option, "1Y", "head"])
+            .fails()
+            .code_is(125)
+            .stderr_contains("stdbuf: invalid mode ‘1Y’: Value too large for defined data type");
+    }
 }
diff --git a/tests/by-util/test_tail.rs b/tests/by-util/test_tail.rs
index b31344c34..8478944e2 100644
--- a/tests/by-util/test_tail.rs
+++ b/tests/by-util/test_tail.rs
@@ -1,6 +1,12 @@
+//  * This file is part of the uutils coreutils package.
+//  *
+//  * For the full copyright and license information, please view the LICENSE
+//  * file that was distributed with this source code.
+
+// spell-checker:ignore (ToDO) abcdefghijklmnopqrstuvwxyz efghijklmnopqrstuvwxyz vwxyz emptyfile
+
 extern crate tail;
 
-use self::tail::parse_size;
 use crate::common::util::*;
 use std::char::from_digit;
 use std::io::Write;
@@ -236,41 +242,6 @@ fn test_bytes_big() {
     }
 }
 
-#[test]
-fn test_parse_size() {
-    // No suffix.
-    assert_eq!(Ok(1234), parse_size("1234"));
-
-    // kB is 1000
-    assert_eq!(Ok(9 * 1000), parse_size("9kB"));
-
-    // K is 1024
-    assert_eq!(Ok(2 * 1024), parse_size("2K"));
-
-    let suffixes = [
-        ('M', 2u32),
-        ('G', 3u32),
-        ('T', 4u32),
-        ('P', 5u32),
-        ('E', 6u32),
-    ];
-
-    for &(c, exp) in &suffixes {
-        let s = format!("2{}B", c);
-        assert_eq!(Ok(2 * (1000_u64).pow(exp)), parse_size(&s));
-
-        let s = format!("2{}", c);
-        assert_eq!(Ok(2 * (1024_u64).pow(exp)), parse_size(&s));
-    }
-
-    // Sizes that are too big.
-    assert!(parse_size("1Z").is_err());
-    assert!(parse_size("1Y").is_err());
-
-    // Bad number
-    assert!(parse_size("328hdsf3290").is_err()); // spell-checker:disable-line
-}
-
 #[test]
 fn test_lines_with_size_suffix() {
     const FILE: &str = "test_lines_with_size_suffix.txt";
@@ -320,12 +291,11 @@ fn test_multiple_input_files_with_suppressed_headers() {
 
 #[test]
 fn test_multiple_input_quiet_flag_overrides_verbose_flag_for_suppressing_headers() {
-    // TODO: actually the later one should win, i.e. -qv should lead to headers being printed, -vq to them being suppressed
     new_ucmd!()
         .arg(FOOBAR_TXT)
         .arg(FOOBAR_2_TXT)
-        .arg("-q")
         .arg("-v")
+        .arg("-q")
         .run()
         .stdout_is_fixture("foobar_multiple_quiet.expected");
 }
@@ -388,3 +358,61 @@ fn test_positive_zero_lines() {
         .succeeds()
         .stdout_is("a\nb\nc\nd\ne\n");
 }
+
+#[test]
+fn test_tail_invalid_num() {
+    new_ucmd!()
+        .args(&["-c", "1024R", "emptyfile.txt"])
+        .fails()
+        .stderr_is("tail: invalid number of bytes: ‘1024R’");
+    new_ucmd!()
+        .args(&["-n", "1024R", "emptyfile.txt"])
+        .fails()
+        .stderr_is("tail: invalid number of lines: ‘1024R’");
+    #[cfg(not(target_pointer_width = "128"))]
+    new_ucmd!()
+        .args(&["-c", "1Y", "emptyfile.txt"])
+        .fails()
+        .stderr_is("tail: invalid number of bytes: ‘1Y’: Value too large for defined data type");
+    #[cfg(not(target_pointer_width = "128"))]
+    new_ucmd!()
+        .args(&["-n", "1Y", "emptyfile.txt"])
+        .fails()
+        .stderr_is("tail: invalid number of lines: ‘1Y’: Value too large for defined data type");
+    #[cfg(target_pointer_width = "32")]
+    {
+        let sizes = ["1000G", "10T"];
+        for size in &sizes {
+            new_ucmd!()
+                .args(&["-c", size])
+                .fails()
+                .code_is(1)
+                .stderr_only(format!(
+                    "tail: invalid number of bytes: ‘{}’: Value too large for defined data type",
+                    size
+                ));
+        }
+    }
+}
+
+#[test]
+fn test_tail_num_with_undocumented_sign_bytes() {
+    // tail: '-' is not documented (8.32 man pages)
+    // head: '+' is not documented (8.32 man pages)
+    const ALPHABET: &str = "abcdefghijklmnopqrstuvwxyz";
+    new_ucmd!()
+        .args(&["-c", "5"])
+        .pipe_in(ALPHABET)
+        .succeeds()
+        .stdout_is("vwxyz");
+    new_ucmd!()
+        .args(&["-c", "-5"])
+        .pipe_in(ALPHABET)
+        .succeeds()
+        .stdout_is("vwxyz");
+    new_ucmd!()
+        .args(&["-c", "+5"])
+        .pipe_in(ALPHABET)
+        .succeeds()
+        .stdout_is("efghijklmnopqrstuvwxyz");
+}
diff --git a/tests/by-util/test_truncate.rs b/tests/by-util/test_truncate.rs
index bb0f4a596..2da59035e 100644
--- a/tests/by-util/test_truncate.rs
+++ b/tests/by-util/test_truncate.rs
@@ -1,3 +1,10 @@
+//  * This file is part of the uutils coreutils package.
+//  *
+//  * For the full copyright and license information, please view the LICENSE
+//  * file that was distributed with this source code.
+
+// spell-checker:ignore (words) RFILE
+
 use crate::common::util::*;
 use std::io::{Seek, SeekFrom, Write};
 
@@ -45,9 +52,18 @@ fn test_reference() {
     let at = &scene.fixtures;
     let mut file = at.make_file(FILE2);
 
-    scene.ucmd().arg("-s").arg("+5KB").arg(FILE1).run();
+    // manpage: "A FILE argument that does not exist is created."
+    // TODO: 'truncate' does not create the file in this case,
+    //        but should because '--no-create' wasn't specified.
+    at.touch(FILE1); // TODO: remove this when 'no-create' is fixed
+    scene.ucmd().arg("-s").arg("+5KB").arg(FILE1).succeeds();
 
-    scene.ucmd().arg("--reference").arg(FILE1).arg(FILE2).run();
+    scene
+        .ucmd()
+        .arg("--reference")
+        .arg(FILE1)
+        .arg(FILE2)
+        .succeeds();
 
     file.seek(SeekFrom::End(0)).unwrap();
     let actual = file.seek(SeekFrom::Current(0)).unwrap();
@@ -231,11 +247,18 @@ fn test_size_and_reference() {
     );
 }
 
+#[test]
+fn test_error_filename_only() {
+    // truncate: you must specify either ‘--size’ or ‘--reference’
+    new_ucmd!().args(&["file"]).fails().stderr_contains(
+        "error: The following required arguments were not provided:
+    --reference <RFILE>
+    --size <SIZE>",
+    );
+}
+
 #[test]
 fn test_invalid_numbers() {
-    // TODO For compatibility with GNU, `truncate -s 0X` should cause
-    // the same error as `truncate -s 0X file`, but currently it returns
-    // a different error.
     new_ucmd!()
         .args(&["-s", "0X", "file"])
         .fails()
@@ -265,3 +288,36 @@ fn test_reference_with_size_file_not_found() {
         .fails()
         .stderr_contains("cannot stat 'a': No such file or directory");
 }
+
+#[test]
+fn test_truncate_bytes_size() {
+    // TODO: this should succeed without error, uncomment when '--no-create' is fixed
+    // new_ucmd!()
+    //     .args(&["--no-create", "--size", "K", "file"])
+    //     .succeeds();
+    new_ucmd!()
+        .args(&["--size", "1024R", "file"])
+        .fails()
+        .code_is(1)
+        .stderr_only("truncate: Invalid number: ‘1024R’");
+    #[cfg(not(target_pointer_width = "128"))]
+    new_ucmd!()
+        .args(&["--size", "1Y", "file"])
+        .fails()
+        .code_is(1)
+        .stderr_only("truncate: Invalid number: ‘1Y’: Value too large for defined data type");
+    #[cfg(target_pointer_width = "32")]
+    {
+        let sizes = ["1000G", "10T"];
+        for size in &sizes {
+            new_ucmd!()
+                .args(&["--size", size, "file"])
+                .fails()
+                .code_is(1)
+                .stderr_only(format!(
+                    "truncate: Invalid number: ‘{}’: Value too large for defined data type",
+                    size
+                ));
+        }
+    }
+}
diff --git a/tests/by-util/test_users.rs b/tests/by-util/test_users.rs
index 8ceb0eeb8..68bdf9a5e 100644
--- a/tests/by-util/test_users.rs
+++ b/tests/by-util/test_users.rs
@@ -13,6 +13,8 @@ fn test_users_check_name() {
     #[cfg(target_vendor = "apple")]
     let util_name = format!("g{}", util_name!());
 
+    // note: clippy::needless_borrow *false positive*
+    #[allow(clippy::needless_borrow)]
     let expected = TestScenario::new(&util_name)
         .cmd_keepenv(util_name)
         .env("LANGUAGE", "C")
diff --git a/tests/by-util/test_who.rs b/tests/by-util/test_who.rs
index 16444b0cb..4907d2306 100644
--- a/tests/by-util/test_who.rs
+++ b/tests/by-util/test_who.rs
@@ -238,6 +238,8 @@ fn expected_result(args: &[&str]) -> String {
     #[cfg(target_vendor = "apple")]
     let util_name = format!("g{}", util_name!());
 
+    // note: clippy::needless_borrow *false positive*
+    #[allow(clippy::needless_borrow)]
     TestScenario::new(&util_name)
         .cmd_keepenv(util_name)
         .env("LANGUAGE", "C")
diff --git a/tests/common/util.rs b/tests/common/util.rs
index 64485c0a8..922d2ba36 100644
--- a/tests/common/util.rs
+++ b/tests/common/util.rs
@@ -641,11 +641,20 @@ impl AtPath {
         // Source:
         // http://stackoverflow.com/questions/31439011/getfinalpathnamebyhandle-without-prepended
         let prefix = "\\\\?\\";
+        // FixME: replace ...
+        #[allow(clippy::manual_strip)]
         if s.starts_with(prefix) {
             String::from(&s[prefix.len()..])
         } else {
             s
         }
+        // ... with ...
+        // if let Some(stripped) = s.strip_prefix(prefix) {
+        //     String::from(stripped)
+        // } else {
+        //     s
+        // }
+        // ... when using MSRV with stabilized `strip_prefix()`
     }
 }
 
diff --git a/tests/fixtures/chgrp/file1 b/tests/fixtures/chgrp/file1
new file mode 100644
index 000000000..73b6f48ab
--- /dev/null
+++ b/tests/fixtures/chgrp/file1
@@ -0,0 +1 @@
+target file 1
diff --git a/tests/fixtures/chgrp/file2 b/tests/fixtures/chgrp/file2
new file mode 100644
index 000000000..7ecd32965
--- /dev/null
+++ b/tests/fixtures/chgrp/file2
@@ -0,0 +1 @@
+target file 2
diff --git a/tests/fixtures/chgrp/file3 b/tests/fixtures/chgrp/file3
new file mode 100644
index 000000000..73d293aba
--- /dev/null
+++ b/tests/fixtures/chgrp/file3
@@ -0,0 +1 @@
+target file 3
diff --git a/tests/fixtures/chgrp/ref_file b/tests/fixtures/chgrp/ref_file
new file mode 100644
index 000000000..aba32d56e
--- /dev/null
+++ b/tests/fixtures/chgrp/ref_file
@@ -0,0 +1 @@
+Reference file
diff --git a/util/build-gnu.sh b/util/build-gnu.sh
index 1ffde8311..798a33456 100644
--- a/util/build-gnu.sh
+++ b/util/build-gnu.sh
@@ -1,16 +1,16 @@
 #!/bin/bash
 
-# spell-checker:ignore (paths) abmon deref discrim getlimits getopt ginstall gnulib inacc infloop inotify reflink ; (misc) INT_OFLOW OFLOW ; (vars/env) BUILDDIR SRCDIR
+# spell-checker:ignore (paths) abmon deref discrim eacces getlimits getopt ginstall gnulib inacc infloop inotify reflink ; (misc) INT_OFLOW OFLOW ; (vars/env) BUILDDIR SRCDIR
 
 set -e
 if test ! -d ../gnu; then
     echo "Could not find ../gnu"
-    echo "git clone git@github.com:coreutils/coreutils.git ../gnu"
+    echo "git clone git@github.com:coreutils/coreutils.git gnu"
     exit 1
 fi
 if test ! -d ../gnulib; then
     echo "Could not find ../gnulib"
-    echo "git clone git@github.com:coreutils/gnulib.git ../gnulib"
+    echo "git clone git@github.com:coreutils/gnulib.git gnulib"
     exit 1
 fi