diff --git a/.github/workflows/CICD.yml b/.github/workflows/CICD.yml
index 32c3537c2..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::${CODECOV_FLAGS}
+        outputs CODECOV_FLAGS
     - name: rust toolchain ~ install
       uses: actions-rs/toolchain@v1
       with:
@@ -563,11 +537,11 @@ jobs:
       shell: bash
       run: |
         ## Dependent VARs setup
+        outputs() { for var in "$@" ; 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 ${CARGO_FEATURES_OPTION})"
         CARGO_UTILITY_LIST_OPTIONS="$(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:
@@ -606,7 +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 0455d7118..c2c3a6242 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -44,13 +44,16 @@ dependencies = [
 ]
 
 [[package]]
-name = "arrayvec"
-version = "0.4.12"
+name = "arrayref"
+version = "0.3.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cd9fd44efafa8690358b7408d253adf110036b88f55672a933f01d616ad9b1b9"
-dependencies = [
- "nodrop",
-]
+checksum = "a4c527152e37cf757a3f78aae5a06fbeefdb07ccc535c980a3208ee3060dd544"
+
+[[package]]
+name = "arrayvec"
+version = "0.5.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "23b62fc65de8e4e7f52534fb52b0f3ed04746ae267519eef2a83941e8085068b"
 
 [[package]]
 name = "atty"
@@ -100,11 +103,12 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "cf1de2fe8c75bc145a2f577add951f8134889b4795d47466a54a5c846d691693"
 
 [[package]]
-name = "blake2-rfc"
-version = "0.2.18"
+name = "blake2b_simd"
+version = "0.5.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5d6d530bdd2d52966a6d03b7a964add7ae1a288d25214066fd4b600f0f796400"
+checksum = "afa748e348ad3be8263be728124b24a24f268266f6f5d58af9d75f6a40b5c587"
 dependencies = [
+ "arrayref",
  "arrayvec",
  "constant_time_eq",
 ]
@@ -700,9 +704,9 @@ checksum = "62aca2aba2d62b4a7f5b33f3712cb1b0692779a56fb510499d5c0aa594daeaf3"
 
 [[package]]
 name = "heck"
-version = "0.3.2"
+version = "0.3.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "87cbf45460356b7deeb5e3415b5563308c0a9b057c85e12b06ad551f98d0a6ac"
+checksum = "6d621efb26863f0e9924c6ac577e8275e5e6b77455db64ffa6c65c904e9e132c"
 dependencies = [
  "unicode-segmentation",
 ]
@@ -1383,12 +1387,9 @@ dependencies = [
 
 [[package]]
 name = "regex-automata"
-version = "0.1.9"
+version = "0.1.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ae1ded71d66a4a97f5e961fd0cb25a5f366a42a41570d16a763a69c092c26ae4"
-dependencies = [
- "byteorder",
-]
+checksum = "6c230d73fb8d8c1b9c0b3135c5142a8acee3a0558fb8db5cf1cb65f8d7862132"
 
 [[package]]
 name = "regex-syntax"
@@ -1501,9 +1502,9 @@ dependencies = [
 
 [[package]]
 name = "signal-hook-registry"
-version = "1.3.0"
+version = "1.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "16f1d0fef1604ba8f7a073c7e701f213e056707210e9020af4528e0101ce11a6"
+checksum = "e51e73328dc4ac0c7ccbda3a494dfa03df1de2f46018127f60c693f2648455b0"
 dependencies = [
  "libc",
 ]
@@ -1771,6 +1772,7 @@ dependencies = [
 name = "uu_cat"
 version = "0.0.6"
 dependencies = [
+ "atty",
  "clap",
  "nix 0.20.0",
  "thiserror",
@@ -1871,6 +1873,7 @@ dependencies = [
 name = "uu_cut"
 version = "0.0.6"
 dependencies = [
+ "atty",
  "bstr",
  "clap",
  "memchr 2.4.0",
@@ -1904,6 +1907,7 @@ dependencies = [
 name = "uu_dircolors"
 version = "0.0.6"
 dependencies = [
+ "clap",
  "glob 0.3.0",
  "uucore",
  "uucore_procs",
@@ -2028,7 +2032,7 @@ dependencies = [
 name = "uu_hashsum"
 version = "0.0.6"
 dependencies = [
- "blake2-rfc",
+ "blake2b_simd",
  "clap",
  "digest",
  "hex",
@@ -2215,6 +2219,8 @@ dependencies = [
  "nix 0.13.1",
  "redox_syscall 0.1.57",
  "redox_termios",
+ "unicode-segmentation",
+ "unicode-width",
  "uucore",
  "uucore_procs",
 ]
@@ -2258,6 +2264,7 @@ dependencies = [
 name = "uu_nohup"
 version = "0.0.6"
 dependencies = [
+ "atty",
  "clap",
  "libc",
  "uucore",
@@ -2416,6 +2423,7 @@ dependencies = [
  "uucore",
  "uucore_procs",
  "walkdir",
+ "winapi 0.3.9",
 ]
 
 [[package]]
@@ -2597,7 +2605,6 @@ name = "uu_timeout"
 version = "0.0.6"
 dependencies = [
  "clap",
- "getopts",
  "libc",
  "uucore",
  "uucore_procs",
@@ -2655,6 +2662,7 @@ dependencies = [
 name = "uu_tty"
 version = "0.0.6"
 dependencies = [
+ "atty",
  "clap",
  "libc",
  "uucore",
diff --git a/Cargo.toml b/Cargo.toml
index 5f89a4077..804c5f978 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -349,9 +349,9 @@ sha1 = { version="0.6", features=["std"] }
 tempfile = "3.2.0"
 time = "0.1"
 unindent = "0.1"
-uucore = { version=">=0.0.8", package="uucore", path="src/uucore", features=["entries"] }
+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/README.md b/README.md
index fde01d64a..fd8709b64 100644
--- a/README.md
+++ b/README.md
@@ -342,22 +342,22 @@ To contribute to uutils, please see [CONTRIBUTING](CONTRIBUTING.md).
 | Done      | Semi-Done | To Do  |
 |-----------|-----------|--------|
 | arch      | cp        | chcon  |
-| base32    | expr      | csplit |
-| base64    | install   | dd     |
-| basename  | ls        | df     |
-| cat       | more      | numfmt |
-| chgrp     | od (`--strings` and 128-bit data types missing) | runcon |
-| chmod     | printf    | stty   |
-| chown     | sort      |        |
-| chroot    | split     |        |
-| cksum     | tail      |        |
-| comm      | test      |        |
-| csplit    | date      |        |
-| cut       | join      |        |
-| dircolors | df        |        |
+| base32    | date      | dd     |
+| base64    | df        | runcon |
+| basename  | expr      | stty   |
+| cat       | install   |        |
+| chgrp     | join      |        |
+| chmod     | ls        |        |
+| chown     | more      |        |
+| chroot    | numfmt    |        |
+| cksum     | od (`--strings` and 128-bit data types missing) | |
+| comm      | pr        |        |
+| csplit    | printf    |        |
+| cut       | sort      |        |
+| dircolors | split     |        |
 | dirname   | tac       |        |
-| du        | pr        |        |
-| echo      |           |        |
+| du        | tail      |        |
+| echo      | test      |        |
 | env       |           |        |
 | expand    |           |        |
 | factor    |           |        |
@@ -374,12 +374,12 @@ To contribute to uutils, please see [CONTRIBUTING](CONTRIBUTING.md).
 | link      |           |        |
 | ln        |           |        |
 | logname   |           |        |
-| ~~md5sum~~ (replaced by [hashsum](https://github.com/uutils/coreutils/blob/master/src/uu/hashsum/src/hashsum.rs)) | |
-| ~~sha1sum~~ (replaced by [hashsum](https://github.com/uutils/coreutils/blob/master/src/uu/hashsum/src/hashsum.rs)) | |
-| ~~sha224sum~~ (replaced by [hashsum](https://github.com/uutils/coreutils/blob/master/src/uu/hashsum/src/hashsum.rs)) | |
-| ~~sha256sum~~ (replaced by [hashsum](https://github.com/uutils/coreutils/blob/master/src/uu/hashsum/src/hashsum.rs)) | |
-| ~~sha384sum~~ (replaced by [hashsum](https://github.com/uutils/coreutils/blob/master/src/uu/hashsum/src/hashsum.rs)) | |
-| ~~sha512sum~~ (replaced by [hashsum](https://github.com/uutils/coreutils/blob/master/src/uu/hashsum/src/hashsum.rs)) | |
+| ~~md5sum~~ (replaced by [hashsum](https://github.com/uutils/coreutils/blob/master/src/uu/hashsum/src/hashsum.rs)) | | |
+| ~~sha1sum~~ (replaced by [hashsum](https://github.com/uutils/coreutils/blob/master/src/uu/hashsum/src/hashsum.rs)) | | |
+| ~~sha224sum~~ (replaced by [hashsum](https://github.com/uutils/coreutils/blob/master/src/uu/hashsum/src/hashsum.rs)) | | |
+| ~~sha256sum~~ (replaced by [hashsum](https://github.com/uutils/coreutils/blob/master/src/uu/hashsum/src/hashsum.rs)) | | |
+| ~~sha384sum~~ (replaced by [hashsum](https://github.com/uutils/coreutils/blob/master/src/uu/hashsum/src/hashsum.rs)) | | |
+| ~~sha512sum~~ (replaced by [hashsum](https://github.com/uutils/coreutils/blob/master/src/uu/hashsum/src/hashsum.rs)) | | |
 | mkdir     |           |        |
 | mkfifo    |           |        |
 | mknod     |           |        |
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/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..47ad3117f 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
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/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..649300d83 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;
diff --git a/src/uu/chroot/src/chroot.rs b/src/uu/chroot/src/chroot.rs
index a05bd4494..8e23d8227 100644
--- a/src/uu/chroot/src/chroot.rs
+++ b/src/uu/chroot/src/chroot.rs
@@ -106,13 +106,13 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
             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.push(v.vals[0].to_str().unwrap());
             }
             vector
         }
     };
 
-    set_context(&newroot, &matches);
+    set_context(newroot, &matches);
 
     let pstatus = Command::new(command[0])
         .args(&command[1..])
@@ -132,7 +132,7 @@ 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/cp/src/cp.rs b/src/uu/cp/src/cp.rs
index 6a114cf44..cc0103044 100644
--- a/src/uu/cp/src/cp.rs
+++ b/src/uu/cp/src/cp.rs
@@ -1088,7 +1088,7 @@ 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(()),
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/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/dircolors/Cargo.toml b/src/uu/dircolors/Cargo.toml
index 5e822820e..7d47fa5c4 100644
--- a/src/uu/dircolors/Cargo.toml
+++ b/src/uu/dircolors/Cargo.toml
@@ -15,6 +15,7 @@ edition = "2018"
 path = "src/dircolors.rs"
 
 [dependencies]
+clap = "2.33"
 glob = "0.3.0"
 uucore = { version=">=0.0.8", package="uucore", path="../../uucore" }
 uucore_procs = { version=">=0.0.5", package="uucore_procs", path="../../uucore_procs" }
diff --git a/src/uu/dircolors/src/dircolors.rs b/src/uu/dircolors/src/dircolors.rs
index b6942c2d2..2fa2e8b91 100644
--- a/src/uu/dircolors/src/dircolors.rs
+++ b/src/uu/dircolors/src/dircolors.rs
@@ -1,6 +1,7 @@
 // This file is part of the uutils coreutils package.
 //
 // (c) Jian Zeng <anonymousknight96@gmail.com>
+// (c) Mitchell Mebane <mitchell.mebane@gmail.com>
 //
 // For the full copyright and license information, please view the LICENSE
 // file that was distributed with this source code.
@@ -15,6 +16,15 @@ use std::env;
 use std::fs::File;
 use std::io::{BufRead, BufReader};
 
+use clap::{crate_version, App, Arg};
+
+mod options {
+    pub const BOURNE_SHELL: &str = "bourne-shell";
+    pub const C_SHELL: &str = "c-shell";
+    pub const PRINT_DATABASE: &str = "print-database";
+    pub const FILE: &str = "FILE";
+}
+
 static SYNTAX: &str = "[OPTION]... [FILE]";
 static SUMMARY: &str = "Output commands to set the LS_COLORS environment variable.";
 static LONG_HELP: &str = "
@@ -52,28 +62,56 @@ pub fn guess_syntax() -> OutputFmt {
     }
 }
 
+fn get_usage() -> String {
+    format!("{0} {1}", executable!(), SYNTAX)
+}
+
 pub fn uumain(args: impl uucore::Args) -> i32 {
     let args = args
         .collect_str(InvalidEncodingHandling::Ignore)
         .accept_any();
 
-    let matches = app!(SYNTAX, SUMMARY, LONG_HELP)
-        .optflag("b", "sh", "output Bourne shell code to set LS_COLORS")
-        .optflag(
-            "",
-            "bourne-shell",
-            "output Bourne shell code to set LS_COLORS",
-        )
-        .optflag("c", "csh", "output C shell code to set LS_COLORS")
-        .optflag("", "c-shell", "output C shell code to set LS_COLORS")
-        .optflag("p", "print-database", "print the byte counts")
-        .parse(args);
+    let usage = get_usage();
 
-    if (matches.opt_present("csh")
-        || matches.opt_present("c-shell")
-        || matches.opt_present("sh")
-        || matches.opt_present("bourne-shell"))
-        && matches.opt_present("print-database")
+    let matches = App::new(executable!())
+        .version(crate_version!())
+        .about(SUMMARY)
+        .usage(&usage[..])
+        .after_help(LONG_HELP)
+        .arg(
+            Arg::with_name(options::BOURNE_SHELL)
+                .long("sh")
+                .short("b")
+                .visible_alias("bourne-shell")
+                .help("output Bourne shell code to set LS_COLORS")
+                .display_order(1),
+        )
+        .arg(
+            Arg::with_name(options::C_SHELL)
+                .long("csh")
+                .short("c")
+                .visible_alias("c-shell")
+                .help("output C shell code to set LS_COLORS")
+                .display_order(2),
+        )
+        .arg(
+            Arg::with_name(options::PRINT_DATABASE)
+                .long("print-database")
+                .short("p")
+                .help("print the byte counts")
+                .display_order(3),
+        )
+        .arg(Arg::with_name(options::FILE).hidden(true).multiple(true))
+        .get_matches_from(&args);
+
+    let files = matches
+        .values_of(options::FILE)
+        .map_or(vec![], |file_values| file_values.collect());
+
+    // clap provides .conflicts_with / .conflicts_with_all, but we want to
+    // manually handle conflicts so we can match the output of GNU coreutils
+    if (matches.is_present(options::C_SHELL) || matches.is_present(options::BOURNE_SHELL))
+        && matches.is_present(options::PRINT_DATABASE)
     {
         show_usage_error!(
             "the options to output dircolors' internal database and\nto select a shell \
@@ -82,12 +120,12 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
         return 1;
     }
 
-    if matches.opt_present("print-database") {
-        if !matches.free.is_empty() {
+    if matches.is_present(options::PRINT_DATABASE) {
+        if !files.is_empty() {
             show_usage_error!(
                 "extra operand ‘{}’\nfile operands cannot be combined with \
                  --print-database (-p)",
-                matches.free[0]
+                files[0]
             );
             return 1;
         }
@@ -96,9 +134,9 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
     }
 
     let mut out_format = OutputFmt::Unknown;
-    if matches.opt_present("csh") || matches.opt_present("c-shell") {
+    if matches.is_present(options::C_SHELL) {
         out_format = OutputFmt::CShell;
-    } else if matches.opt_present("sh") || matches.opt_present("bourne-shell") {
+    } else if matches.is_present(options::BOURNE_SHELL) {
         out_format = OutputFmt::Shell;
     }
 
@@ -113,24 +151,20 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
     }
 
     let result;
-    if matches.free.is_empty() {
+    if files.is_empty() {
         result = parse(INTERNAL_DB.lines(), out_format, "")
     } else {
-        if matches.free.len() > 1 {
-            show_usage_error!("extra operand ‘{}’", matches.free[1]);
+        if files.len() > 1 {
+            show_usage_error!("extra operand ‘{}’", files[1]);
             return 1;
         }
-        match File::open(matches.free[0].as_str()) {
+        match File::open(files[0]) {
             Ok(f) => {
                 let fin = BufReader::new(f);
-                result = parse(
-                    fin.lines().filter_map(Result::ok),
-                    out_format,
-                    matches.free[0].as_str(),
-                )
+                result = parse(fin.lines().filter_map(Result::ok), out_format, files[0])
             }
             Err(e) => {
-                show_error!("{}: {}", matches.free[0], e);
+                show_error!("{}: {}", files[0], e);
                 return 1;
             }
         }
diff --git a/src/uu/du/src/du.rs b/src/uu/du/src/du.rs
index a46f74100..94d90c6cd 100644
--- a/src/uu/du/src/du.rs
+++ b/src/uu/du/src/du.rs
@@ -24,6 +24,8 @@ 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::InvalidEncodingHandling;
@@ -159,7 +161,7 @@ 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 +193,7 @@ 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) {
@@ -256,7 +258,7 @@ fn unit_string_to_number(s: &str) -> Option<u64> {
 
 fn translate_to_pure_number(s: &Option<&str>) -> Option<u64> {
     match *s {
-        Some(ref s) => unit_string_to_number(s),
+        Some(s) => unit_string_to_number(s),
         None => None,
     }
 }
@@ -318,8 +320,7 @@ fn du(
                         if this_stat.is_dir {
                             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 +359,9 @@ 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())
@@ -431,6 +434,7 @@ 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 test suite uses this alias
         )
         .arg(
             Arg::with_name(options::BLOCK_SIZE)
@@ -582,12 +586,12 @@ 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 */ }
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..e20f047b7 100644
--- a/src/uu/env/src/env.rs
+++ b/src/uu/env/src/env.rs
@@ -245,7 +245,7 @@ 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);
     }
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..ba477414e 100644
--- a/src/uu/expr/src/syntax_tree.rs
+++ b/src/uu/expr/src/syntax_tree.rs
@@ -175,23 +175,14 @@ 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 +196,7 @@ pub fn tokens_to_ast(
             maybe_dump_ast(&result);
             result
         }
-    }
+    })
 }
 
 fn maybe_dump_ast(result: &Result<Box<AstNode>, 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/groups/src/groups.rs b/src/uu/groups/src/groups.rs
index 5b9cd948a..07c25cebb 100644
--- a/src/uu/groups/src/groups.rs
+++ b/src/uu/groups/src/groups.rs
@@ -10,7 +10,7 @@
 
 #[macro_use]
 extern crate uucore;
-use uucore::entries::{get_groups, gid2grp, Locate, Passwd};
+use uucore::entries::{get_groups_gnu, gid2grp, Locate, Passwd};
 
 use clap::{crate_version, App, Arg};
 
@@ -35,7 +35,7 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
         None => {
             println!(
                 "{}",
-                get_groups()
+                get_groups_gnu(None)
                     .unwrap()
                     .iter()
                     .map(|&g| gid2grp(g).unwrap())
diff --git a/src/uu/hashsum/BENCHMARKING.md b/src/uu/hashsum/BENCHMARKING.md
new file mode 100644
index 000000000..cef710a19
--- /dev/null
+++ b/src/uu/hashsum/BENCHMARKING.md
@@ -0,0 +1,9 @@
+## Benchmarking hashsum
+
+### To bench blake2
+
+Taken from: https://github.com/uutils/coreutils/pull/2296
+
+With a large file:
+$ hyperfine "./target/release/coreutils hashsum --b2sum large-file" "b2sum large-file"
+
diff --git a/src/uu/hashsum/Cargo.toml b/src/uu/hashsum/Cargo.toml
index 04a22cac7..11388ebf8 100644
--- a/src/uu/hashsum/Cargo.toml
+++ b/src/uu/hashsum/Cargo.toml
@@ -25,7 +25,7 @@ regex-syntax = "0.6.7"
 sha1 = "0.6.0"
 sha2 = "0.6.0"
 sha3 = "0.6.0"
-blake2-rfc = "0.2.18"
+blake2b_simd = "0.5.11"
 uucore = { version=">=0.0.8", package="uucore", path="../../uucore" }
 uucore_procs = { version=">=0.0.5", package="uucore_procs", path="../../uucore_procs" }
 
diff --git a/src/uu/hashsum/src/digest.rs b/src/uu/hashsum/src/digest.rs
index 218de0a36..9093d94a7 100644
--- a/src/uu/hashsum/src/digest.rs
+++ b/src/uu/hashsum/src/digest.rs
@@ -1,4 +1,3 @@
-extern crate blake2_rfc;
 extern crate digest;
 extern crate md5;
 extern crate sha1;
@@ -49,9 +48,9 @@ impl Digest for md5::Context {
     }
 }
 
-impl Digest for blake2_rfc::blake2b::Blake2b {
+impl Digest for blake2b_simd::State {
     fn new() -> Self {
-        blake2_rfc::blake2b::Blake2b::new(64)
+        Self::new()
     }
 
     fn input(&mut self, input: &[u8]) {
@@ -59,12 +58,12 @@ impl Digest for blake2_rfc::blake2b::Blake2b {
     }
 
     fn result(&mut self, out: &mut [u8]) {
-        let hash_result = &self.clone().finalize();
-        out.copy_from_slice(&hash_result.as_bytes());
+        let hash_result = &self.finalize();
+        out.copy_from_slice(hash_result.as_bytes());
     }
 
     fn reset(&mut self) {
-        *self = blake2_rfc::blake2b::Blake2b::new(64);
+        *self = Self::new();
     }
 
     fn output_bits(&self) -> usize {
diff --git a/src/uu/hashsum/src/hashsum.rs b/src/uu/hashsum/src/hashsum.rs
index b39b5788c..a007473ab 100644
--- a/src/uu/hashsum/src/hashsum.rs
+++ b/src/uu/hashsum/src/hashsum.rs
@@ -19,7 +19,6 @@ mod digest;
 
 use self::digest::Digest;
 
-use blake2_rfc::blake2b::Blake2b;
 use clap::{App, Arg, ArgMatches};
 use hex::ToHex;
 use md5::Context as Md5;
@@ -85,9 +84,13 @@ fn detect_algo<'a>(
         "sha256sum" => ("SHA256", Box::new(Sha256::new()) as Box<dyn Digest>, 256),
         "sha384sum" => ("SHA384", Box::new(Sha384::new()) as Box<dyn Digest>, 384),
         "sha512sum" => ("SHA512", Box::new(Sha512::new()) as Box<dyn Digest>, 512),
-        "b2sum" => ("BLAKE2", Box::new(Blake2b::new(64)) as Box<dyn Digest>, 512),
+        "b2sum" => (
+            "BLAKE2",
+            Box::new(blake2b_simd::State::new()) as Box<dyn Digest>,
+            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>,
@@ -137,7 +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>,
@@ -148,7 +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>,
@@ -187,11 +190,11 @@ fn detect_algo<'a>(
                     set_or_crash("SHA512", Box::new(Sha512::new()), 512)
                 }
                 if matches.is_present("b2sum") {
-                    set_or_crash("BLAKE2", Box::new(Blake2b::new(64)), 512)
+                    set_or_crash("BLAKE2", Box::new(blake2b_simd::State::new()), 512)
                 }
                 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>,
@@ -235,7 +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),
                         },
@@ -244,7 +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),
                         },
@@ -252,10 +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/id/src/id.rs b/src/uu/id/src/id.rs
index 77b185f24..4f8f92fe4 100644
--- a/src/uu/id/src/id.rs
+++ b/src/uu/id/src/id.rs
@@ -10,7 +10,7 @@
 //  http://ftp-archive.freebsd.org/mirror/FreeBSD-Archive/old-releases/i386/1.0-RELEASE/ports/shellutils/src/id.c
 //  http://www.opensource.apple.com/source/shell_cmds/shell_cmds-118/id/id.c
 
-// spell-checker:ignore (ToDO) asid auditid auditinfo auid cstr egid emod euid getaudit getlogin gflag nflag pline rflag termid uflag
+// spell-checker:ignore (ToDO) asid auditid auditinfo auid cstr egid emod euid getaudit getlogin gflag nflag pline rflag termid uflag gsflag
 
 #![allow(non_camel_case_types)]
 #![allow(dead_code)]
@@ -79,7 +79,7 @@ static OPT_GROUPS: &str = "groups";
 static OPT_HUMAN_READABLE: &str = "human-readable";
 static OPT_NAME: &str = "name";
 static OPT_PASSWORD: &str = "password";
-static OPT_REAL_ID: &str = "real-id";
+static OPT_REAL_ID: &str = "real";
 
 static ARG_USERS: &str = "users";
 
@@ -135,7 +135,10 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
         .arg(
             Arg::with_name(OPT_REAL_ID)
                 .short("r")
-                .help("Display the real ID for the -g and -u options"),
+                .long(OPT_REAL_ID)
+                .help(
+                "Display the real ID for the -G, -g and -u options instead of the effective ID.",
+            ),
         )
         .arg(Arg::with_name(ARG_USERS).multiple(true).takes_value(true))
         .get_matches_from(args);
@@ -162,6 +165,7 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
     let nflag = matches.is_present(OPT_NAME);
     let uflag = matches.is_present(OPT_EFFECTIVE_USER);
     let gflag = matches.is_present(OPT_GROUP);
+    let gsflag = matches.is_present(OPT_GROUPS);
     let rflag = matches.is_present(OPT_REAL_ID);
 
     if gflag {
@@ -194,26 +198,23 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
         return 0;
     }
 
-    if matches.is_present(OPT_GROUPS) {
+    if gsflag {
+        let id = possible_pw
+            .map(|p| p.gid())
+            .unwrap_or(if rflag { getgid() } else { getegid() });
         println!(
             "{}",
-            if nflag {
-                possible_pw
-                    .map(|p| p.belongs_to())
-                    .unwrap_or_else(|| entries::get_groups().unwrap())
-                    .iter()
-                    .map(|&id| entries::gid2grp(id).unwrap())
-                    .collect::<Vec<_>>()
-                    .join(" ")
-            } else {
-                possible_pw
-                    .map(|p| p.belongs_to())
-                    .unwrap_or_else(|| entries::get_groups().unwrap())
-                    .iter()
-                    .map(|&id| id.to_string())
-                    .collect::<Vec<_>>()
-                    .join(" ")
-            }
+            possible_pw
+                .map(|p| p.belongs_to())
+                .unwrap_or_else(|| entries::get_groups_gnu(Some(id)).unwrap())
+                .iter()
+                .map(|&id| if nflag {
+                    entries::gid2grp(id).unwrap_or_else(|_| id.to_string())
+                } else {
+                    id.to_string()
+                })
+                .collect::<Vec<_>>()
+                .join(" ")
         );
         return 0;
     }
@@ -280,7 +281,7 @@ fn pretty(possible_pw: Option<Passwd>) {
 
         println!(
             "groups\t{}",
-            entries::get_groups()
+            entries::get_groups_gnu(None)
                 .unwrap()
                 .iter()
                 .map(|&gr| entries::gid2grp(gr).unwrap())
diff --git a/src/uu/install/src/install.rs b/src/uu/install/src/install.rs
index 7aa6f95ff..bcfe1a396 100644
--- a/src/uu/install/src/install.rs
+++ b/src/uu/install/src/install.rs
@@ -379,7 +379,7 @@ 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 +422,7 @@ 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 +501,7 @@ 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 +563,7 @@ 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 c282c6844..4b19565a9 100644
--- a/src/uu/ln/src/ln.rs
+++ b/src/uu/ln/src/ln.rs
@@ -259,17 +259,17 @@ 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);
         }
     }
 
@@ -393,7 +393,7 @@ 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()
     };
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 9b1a3d7b6..af6781876 100644
--- a/src/uu/more/Cargo.toml
+++ b/src/uu/more/Cargo.toml
@@ -19,7 +19,9 @@ 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"
 
 [target.'cfg(target_os = "redox")'.dependencies]
 redox_termios = "0.1"
diff --git a/src/uu/more/src/more.rs b/src/uu/more/src/more.rs
index deadba4e4..4d345e96b 100644
--- a/src/uu/more/src/more.rs
+++ b/src/uu/more/src/more.rs
@@ -29,6 +29,9 @@ use crossterm::{
     terminal,
 };
 
+use unicode_segmentation::UnicodeSegmentation;
+use unicode_width::UnicodeWidthStr;
+
 pub mod options {
     pub const SILENT: &str = "silent";
     pub const LOGICAL: &str = "logical";
@@ -140,7 +143,9 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
     if let Some(files) = matches.values_of(options::FILES) {
         let mut stdout = setup_term();
         let length = files.len();
-        for (idx, file) in files.enumerate() {
+
+        let mut files_iter = files.peekable();
+        while let (Some(file), next_file) = (files_iter.next(), files_iter.peek()) {
             let file = Path::new(file);
             if file.is_dir() {
                 terminal::disable_raw_mode().unwrap();
@@ -157,15 +162,14 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
             }
             let mut reader = BufReader::new(File::open(file).unwrap());
             reader.read_to_string(&mut buff).unwrap();
-            let is_last = idx + 1 == length;
-            more(&buff, &mut stdout, is_last);
+            more(&buff, &mut stdout, next_file.copied());
             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, true);
+        more(&buff, &mut stdout, None);
         reset_term(&mut stdout);
     } else {
         show_usage_error!("bad usage");
@@ -200,7 +204,7 @@ fn reset_term(stdout: &mut std::io::Stdout) {
 #[inline(always)]
 fn reset_term(_: &mut usize) {}
 
-fn more(buff: &str, mut stdout: &mut Stdout, is_last: bool) {
+fn more(buff: &str, mut stdout: &mut Stdout, next_file: Option<&str>) {
     let (cols, rows) = terminal::size().unwrap();
     let lines = break_buff(buff, usize::from(cols));
     let line_count: u16 = lines.len().try_into().unwrap();
@@ -214,8 +218,11 @@ fn more(buff: &str, mut stdout: &mut Stdout, is_last: bool) {
         &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.
@@ -267,6 +274,7 @@ fn more(buff: &str, mut stdout: &mut Stdout, is_last: bool) {
                 &mut stdout,
                 lines.clone(),
                 line_count,
+                next_file,
             );
 
             if lines_left == 0 {
@@ -285,6 +293,7 @@ fn draw(
     mut stdout: &mut std::io::Stdout,
     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);
@@ -299,7 +308,7 @@ fn draw(
             .write_all(format!("\r{}\n", line).as_bytes())
             .unwrap();
     }
-    make_prompt_and_flush(&mut stdout, lower_mark, lc);
+    make_prompt_and_flush(&mut stdout, lower_mark, lc, next_file);
     *upper_mark = up_mark;
 }
 
@@ -313,23 +322,30 @@ fn break_buff(buff: &str, cols: usize) -> Vec<String> {
     lines
 }
 
-fn break_line(mut line: &str, cols: usize) -> Vec<String> {
-    let breaks = (line.len() / cols).saturating_add(1);
-    let mut lines = Vec::with_capacity(breaks);
-    // TODO: Use unicode width instead of the length in bytes.
-    if line.len() < cols {
+fn break_line(line: &str, cols: usize) -> Vec<String> {
+    let width = UnicodeWidthStr::width(line);
+    let mut lines = Vec::new();
+    if width < cols {
         lines.push(line.to_string());
         return lines;
     }
 
-    for _ in 1..=breaks {
-        let (line1, line2) = line.split_at(cols);
-        lines.push(line1.to_string());
-        if line2.len() < cols {
-            lines.push(line2.to_string());
-            break;
+    let gr_idx = UnicodeSegmentation::grapheme_indices(line, true);
+    let mut last_index = 0;
+    let mut total_width = 0;
+    for (index, grapheme) in gr_idx {
+        let width = UnicodeWidthStr::width(grapheme);
+        total_width += width;
+
+        if total_width > cols {
+            lines.push(line[last_index..index].to_string());
+            last_index = index;
+            total_width = width;
         }
-        line = line2;
+    }
+
+    if last_index != line.len() {
+        lines.push(line[last_index..].to_string());
     }
     lines
 }
@@ -339,7 +355,7 @@ 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);
+        upper_mark = line_count.saturating_sub(rows).saturating_add(1);
         lower_mark = line_count;
     } else {
         lower_mark = lower_mark.saturating_sub(1)
@@ -348,12 +364,20 @@ fn calc_range(mut upper_mark: u16, rows: u16, line_count: u16) -> (u16, u16) {
 }
 
 // Make a prompt similar to original more
-fn make_prompt_and_flush(stdout: &mut Stdout, lower_mark: u16, lc: u16) {
+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--({}%){}",
+        "\r{}--More--({}){}",
         Attribute::Reverse,
-        ((lower_mark as f64 / lc as f64) * 100.0).round() as u16,
+        status,
         Attribute::Reset
     )
     .unwrap();
@@ -363,13 +387,14 @@ fn make_prompt_and_flush(stdout: &mut Stdout, lower_mark: u16, lc: u16) {
 #[cfg(test)]
 mod tests {
     use super::{break_line, calc_range};
+    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!((75, 100), calc_range(85, 25, 100));
+        assert_eq!((76, 100), calc_range(85, 25, 100));
     }
     #[test]
     fn test_break_lines_long() {
@@ -379,11 +404,12 @@ mod tests {
         }
 
         let lines = break_line(&test_string, 80);
+        let widths: Vec<usize> = lines
+            .iter()
+            .map(|s| UnicodeWidthStr::width(&s[..]))
+            .collect();
 
-        assert_eq!(
-            (80, 80, 40),
-            (lines[0].len(), lines[1].len(), lines[2].len())
-        );
+        assert_eq!((80, 80, 40), (widths[0], widths[1], widths[2]));
     }
 
     #[test]
@@ -397,4 +423,22 @@ mod tests {
 
         assert_eq!(20, lines[0].len());
     }
+
+    #[test]
+    fn test_break_line_zwj() {
+        let mut test_string = String::with_capacity(1100);
+        for _ in 0..20 {
+            test_string.push_str("👩🏻‍🔬");
+        }
+
+        let lines = break_line(&test_string, 80);
+
+        let widths: Vec<usize> = lines
+            .iter()
+            .map(|s| UnicodeWidthStr::width(&s[..]))
+            .collect();
+
+        // Each 👩🏻‍🔬 is 6 character width it break line to the closest number to 80 => 6 * 13 = 78
+        assert_eq!((78, 42), (widths[0], widths[1]));
+    }
 }
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/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..1e7b4533a 100644
--- a/src/uu/od/src/od.rs
+++ b/src/uu/od/src/od.rs
@@ -130,7 +130,7 @@ impl OdOptions {
 
         let mut skip_bytes = match matches.value_of(options::SKIP_BYTES) {
             None => 0,
-            Some(s) => match parse_number_of_bytes(&s) {
+            Some(s) => match parse_number_of_bytes(s) {
                 Ok(i) => i,
                 Err(_) => {
                     return Err(format!("Invalid argument --skip-bytes={}", s));
@@ -176,7 +176,7 @@ impl OdOptions {
 
         let read_bytes = match matches.value_of(options::READ_BYTES) {
             None => None,
-            Some(s) => match parse_number_of_bytes(&s) {
+            Some(s) => match parse_number_of_bytes(s) {
                 Ok(i) => Some(i),
                 Err(_) => {
                     return Err(format!("Invalid argument --read-bytes={}", s));
@@ -537,7 +537,7 @@ where
                     print_bytes(
                         &input_offset.format_byte_offset(),
                         &memory_decoder,
-                        &output_info,
+                        output_info,
                     );
                 }
 
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..ccac44d72 100644
--- a/src/uu/od/src/parse_formats.rs
+++ b/src/uu/od/src/parse_formats.rs
@@ -275,17 +275,13 @@ 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);
 
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/pathchk/src/pathchk.rs b/src/uu/pathchk/src/pathchk.rs
index 9667e0ba1..07e3a3289 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 '{}'",
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..0761dd09d 100644
--- a/src/uu/pr/src/pr.rs
+++ b/src/uu/pr/src/pr.rs
@@ -410,7 +410,7 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
         let options = &result_options.unwrap();
 
         let cmd_result = if file_group.len() == 1 {
-            pr(&file_group.get(0).unwrap(), options)
+            pr(file_group.get(0).unwrap(), options)
         } else {
             mpr(&file_group, options)
         };
@@ -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/float_common.rs b/src/uu/printf/src/tokenize/num_format/formatters/float_common.rs
index dd8259233..dfd64296c 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
@@ -298,11 +298,11 @@ 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..05cc66d51 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() {
diff --git a/src/uu/shred/src/shred.rs b/src/uu/shred/src/shred.rs
index 6a43ed478..964e68a9e 100644
--- a/src/uu/shred/src/shred.rs
+++ b/src/uu/shred/src/shred.rs
@@ -381,7 +381,7 @@ 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 +659,7 @@ 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/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 23567833b..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,
@@ -102,17 +102,17 @@ pub fn read(
         carry_over.clear();
         carry_over.extend_from_slice(&buffer[read..]);
 
-        let payload = Chunk::new(buffer, |buf| {
-            let mut lines = unsafe {
-                // SAFETY: It is safe to transmute to a vector of lines with shorter lifetime,
-                // because it was only temporarily transmuted to a Vec<Line<'static>> to make recycling possible.
-                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);
-            lines
-        });
-        if !payload.borrow_lines().is_empty() {
+        if read != 0 {
+            let payload = Chunk::new(buffer, |buf| {
+                let mut lines = unsafe {
+                    // SAFETY: It is safe to transmute to a vector of lines with shorter lifetime,
+                    // because it was only temporarily transmuted to a Vec<Line<'static>> to make recycling possible.
+                    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);
+                lines
+            });
             sender.send(payload).unwrap();
         }
         if !should_continue {
@@ -175,6 +175,7 @@ fn read_to_buffer(
     separator: u8,
 ) -> (usize, bool) {
     let mut read_target = &mut buffer[start_offset..];
+    let mut last_file_target_size = read_target.len();
     loop {
         match file.read(read_target) {
             Ok(0) => {
@@ -193,7 +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.
@@ -208,14 +209,27 @@ fn read_to_buffer(
                         read_target = &mut buffer[len..];
                     }
                 } else {
-                    // This file is empty.
+                    // This file has been fully read.
+                    let mut leftover_len = read_target.len();
+                    if last_file_target_size != leftover_len {
+                        // The file was not empty.
+                        let read_len = buffer.len() - leftover_len;
+                        if buffer[read_len - 1] != separator {
+                            // The file did not end with a separator. We have to insert one.
+                            buffer[read_len] = separator;
+                            leftover_len -= 1;
+                        }
+                        let read_len = buffer.len() - leftover_len;
+                        read_target = &mut buffer[read_len..];
+                    }
                     if let Some(next_file) = next_files.next() {
                         // There is another file.
+                        last_file_target_size = leftover_len;
                         *file = next_file;
                     } else {
                         // This was the last file.
-                        let leftover_len = read_target.len();
-                        return (buffer.len() - leftover_len, false);
+                        let read_len = buffer.len() - leftover_len;
+                        return (read_len, false);
                     }
                 }
             }
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/ext_sort.rs b/src/uu/sort/src/ext_sort.rs
index 9b1845efa..c439adcdc 100644
--- a/src/uu/sort/src/ext_sort.rs
+++ b/src/uu/sort/src/ext_sort.rs
@@ -12,8 +12,12 @@
 //! The buffers for the individual chunks are recycled. There are two buffers.
 
 use std::cmp::Ordering;
+use std::fs::File;
+use std::io::BufReader;
 use std::io::{BufWriter, Write};
 use std::path::Path;
+use std::process::Child;
+use std::process::{Command, Stdio};
 use std::{
     fs::OpenOptions,
     io::Read,
@@ -25,12 +29,13 @@ use itertools::Itertools;
 
 use tempfile::TempDir;
 
+use crate::Line;
 use crate::{
     chunks::{self, Chunk},
     compare_by, merge, output_sorted_lines, sort_by, GlobalSettings,
 };
 
-const MIN_BUFFER_SIZE: usize = 8_000;
+const START_BUFFER_SIZE: usize = 8_000;
 
 /// Sort files by using auxiliary files for storing intermediate chunks (if needed), and output the result.
 pub fn ext_sort(files: &mut impl Iterator<Item = Box<dyn Read + Send>>, settings: &GlobalSettings) {
@@ -63,10 +68,31 @@ pub fn ext_sort(files: &mut impl Iterator<Item = Box<dyn Read + Send>>, settings
     );
     match read_result {
         ReadResult::WroteChunksToFile { chunks_written } => {
-            let files = (0..chunks_written)
-                .map(|chunk_num| tmp_dir.path().join(chunk_num.to_string()))
-                .collect::<Vec<_>>();
-            let mut merger = merge::merge(&files, settings);
+            let mut children = Vec::new();
+            let files = (0..chunks_written).map(|chunk_num| {
+                let file_path = tmp_dir.path().join(chunk_num.to_string());
+                let file = File::open(file_path).unwrap();
+                if let Some(compress_prog) = &settings.compress_prog {
+                    let mut command = Command::new(compress_prog);
+                    command.stdin(file).stdout(Stdio::piped()).arg("-d");
+                    let mut child = crash_if_err!(
+                        2,
+                        command.spawn().map_err(|err| format!(
+                            "couldn't execute compress program: errno {}",
+                            err.raw_os_error().unwrap()
+                        ))
+                    );
+                    let child_stdout = child.stdout.take().unwrap();
+                    children.push(child);
+                    Box::new(BufReader::new(child_stdout)) as Box<dyn Read + Send>
+                } else {
+                    Box::new(BufReader::new(file)) as Box<dyn Read + Send>
+                }
+            });
+            let mut merger = merge::merge_with_file_limit(files, settings);
+            for child in children {
+                assert_child_success(child, settings.compress_prog.as_ref().unwrap());
+            }
             merger.write_all(settings);
         }
         ReadResult::SortedSingleChunk(chunk) => {
@@ -132,7 +158,14 @@ fn reader_writer(
     for _ in 0..2 {
         chunks::read(
             &mut sender_option,
-            vec![0; MIN_BUFFER_SIZE],
+            vec![
+                0;
+                if START_BUFFER_SIZE < buffer_size {
+                    START_BUFFER_SIZE
+                } else {
+                    buffer_size
+                }
+            ],
             Some(buffer_size),
             &mut carry_over,
             &mut file,
@@ -171,6 +204,7 @@ fn reader_writer(
         write(
             &mut chunk,
             &tmp_dir.path().join(file_number.to_string()),
+            settings.compress_prog.as_deref(),
             separator,
         );
 
@@ -193,14 +227,45 @@ fn reader_writer(
 }
 
 /// Write the lines in `chunk` to `file`, separated by `separator`.
-fn write(chunk: &mut Chunk, file: &Path, separator: u8) {
+/// `compress_prog` is used to optionally compress file contents.
+fn write(chunk: &mut Chunk, file: &Path, compress_prog: Option<&str>, separator: u8) {
     chunk.with_lines_mut(|lines| {
         // Write the lines to the file
         let file = crash_if_err!(1, OpenOptions::new().create(true).write(true).open(file));
-        let mut writer = BufWriter::new(file);
-        for s in lines.iter() {
-            crash_if_err!(1, writer.write_all(s.line.as_bytes()));
-            crash_if_err!(1, writer.write_all(&[separator]));
-        }
+        if let Some(compress_prog) = compress_prog {
+            let mut command = Command::new(compress_prog);
+            command.stdin(Stdio::piped()).stdout(file);
+            let mut child = crash_if_err!(
+                2,
+                command.spawn().map_err(|err| format!(
+                    "couldn't execute compress program: errno {}",
+                    err.raw_os_error().unwrap()
+                ))
+            );
+            let mut writer = BufWriter::new(child.stdin.take().unwrap());
+            write_lines(lines, &mut writer, separator);
+            writer.flush().unwrap();
+            drop(writer);
+            assert_child_success(child, compress_prog);
+        } else {
+            let mut writer = BufWriter::new(file);
+            write_lines(lines, &mut writer, separator);
+        };
     });
 }
+
+fn write_lines<'a, T: Write>(lines: &[Line<'a>], writer: &mut T, separator: u8) {
+    for s in lines {
+        crash_if_err!(1, writer.write_all(s.line.as_bytes()));
+        crash_if_err!(1, writer.write_all(&[separator]));
+    }
+}
+
+fn assert_child_success(mut child: Child, program: &str) {
+    if !matches!(
+        child.wait().map(|e| e.code()),
+        Ok(Some(0)) | Ok(None) | Err(_)
+    ) {
+        crash!(2, "'{}' terminated abnormally", program)
+    }
+}
diff --git a/src/uu/sort/src/merge.rs b/src/uu/sort/src/merge.rs
index 696353829..478b454b6 100644
--- a/src/uu/sort/src/merge.rs
+++ b/src/uu/sort/src/merge.rs
@@ -9,8 +9,8 @@
 
 use std::{
     cmp::Ordering,
-    ffi::OsStr,
-    io::{Read, Write},
+    fs::File,
+    io::{BufWriter, Read, Write},
     iter,
     rc::Rc,
     sync::mpsc::{channel, sync_channel, Receiver, Sender, SyncSender},
@@ -18,18 +18,69 @@ use std::{
 };
 
 use compare::Compare;
+use itertools::Itertools;
 
 use crate::{
     chunks::{self, Chunk},
-    compare_by, open, GlobalSettings,
+    compare_by, GlobalSettings,
 };
 
 // Merge already sorted files.
-pub fn merge<'a>(files: &[impl AsRef<OsStr>], settings: &'a GlobalSettings) -> FileMerger<'a> {
+pub fn merge_with_file_limit<F: ExactSizeIterator<Item = Box<dyn Read + Send>>>(
+    files: F,
+    settings: &GlobalSettings,
+) -> FileMerger {
+    if files.len() > settings.merge_batch_size {
+        let tmp_dir = tempfile::Builder::new()
+            .prefix("uutils_sort")
+            .tempdir_in(&settings.tmp_dir)
+            .unwrap();
+        let mut batch_number = 0;
+        let mut remaining_files = files.len();
+        let batches = files.chunks(settings.merge_batch_size);
+        let mut batches = batches.into_iter();
+        while batch_number + remaining_files > settings.merge_batch_size && remaining_files != 0 {
+            remaining_files = remaining_files.saturating_sub(settings.merge_batch_size);
+            let mut merger = merge_without_limit(batches.next().unwrap(), settings);
+            let tmp_file = File::create(tmp_dir.path().join(batch_number.to_string())).unwrap();
+            merger.write_all_to(settings, &mut BufWriter::new(tmp_file));
+            batch_number += 1;
+        }
+        let batch_files = (0..batch_number).map(|n| {
+            Box::new(File::open(tmp_dir.path().join(n.to_string())).unwrap())
+                as Box<dyn Read + Send>
+        });
+        if batch_number > settings.merge_batch_size {
+            assert!(batches.next().is_none());
+            merge_with_file_limit(
+                Box::new(batch_files) as Box<dyn ExactSizeIterator<Item = Box<dyn Read + Send>>>,
+                settings,
+            )
+        } else {
+            let final_batch = batches.next();
+            assert!(batches.next().is_none());
+            merge_without_limit(
+                batch_files.chain(final_batch.into_iter().flatten()),
+                settings,
+            )
+        }
+    } else {
+        merge_without_limit(files, settings)
+    }
+}
+
+/// Merge files without limiting how many files are concurrently open
+///
+/// It is the responsibility of the caller to ensure that `files` yields only
+/// as many files as we are allowed to open concurrently.
+fn merge_without_limit<F: Iterator<Item = Box<dyn Read + Send>>>(
+    files: F,
+    settings: &GlobalSettings,
+) -> FileMerger {
     let (request_sender, request_receiver) = channel();
-    let mut reader_files = Vec::with_capacity(files.len());
-    let mut loaded_receivers = Vec::with_capacity(files.len());
-    for (file_number, file) in files.iter().map(open).enumerate() {
+    let mut reader_files = Vec::with_capacity(files.size_hint().0);
+    let mut loaded_receivers = Vec::with_capacity(files.size_hint().0);
+    for (file_number, file) in files.enumerate() {
         let (sender, receiver) = sync_channel(2);
         loaded_receivers.push(receiver);
         reader_files.push(ReaderFile {
@@ -146,7 +197,11 @@ impl<'a> FileMerger<'a> {
     /// Write the merged contents to the output file.
     pub fn write_all(&mut self, settings: &GlobalSettings) {
         let mut out = settings.out_writer();
-        while self.write_next(settings, &mut out) {}
+        self.write_all_to(settings, &mut out);
+    }
+
+    pub fn write_all_to(&mut self, settings: &GlobalSettings, out: &mut impl Write) {
+        while self.write_next(settings, out) {}
     }
 
     fn write_next(&mut self, settings: &GlobalSettings, out: &mut impl Write) -> bool {
diff --git a/src/uu/sort/src/sort.rs b/src/uu/sort/src/sort.rs
index 5825e73bd..53619d0d6 100644
--- a/src/uu/sort/src/sort.rs
+++ b/src/uu/sort/src/sort.rs
@@ -95,6 +95,8 @@ static OPT_PARALLEL: &str = "parallel";
 static OPT_FILES0_FROM: &str = "files0-from";
 static OPT_BUF_SIZE: &str = "buffer-size";
 static OPT_TMP_DIR: &str = "temporary-directory";
+static OPT_COMPRESS_PROG: &str = "compress-program";
+static OPT_BATCH_SIZE: &str = "batch-size";
 
 static ARG_FILES: &str = "files";
 
@@ -155,6 +157,8 @@ pub struct GlobalSettings {
     zero_terminated: bool,
     buffer_size: usize,
     tmp_dir: PathBuf,
+    compress_prog: Option<String>,
+    merge_batch_size: usize,
 }
 
 impl GlobalSettings {
@@ -223,6 +227,8 @@ impl Default for GlobalSettings {
             zero_terminated: false,
             buffer_size: DEFAULT_BUF_SIZE,
             tmp_dir: PathBuf::new(),
+            compress_prog: None,
+            merge_batch_size: 16,
         }
     }
 }
@@ -394,9 +400,9 @@ 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
@@ -750,7 +756,7 @@ 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
         {
@@ -840,7 +846,7 @@ 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)) => {
@@ -1076,6 +1082,19 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
                 .takes_value(true)
                 .value_name("DIR"),
         )
+        .arg(
+            Arg::with_name(OPT_COMPRESS_PROG)
+                .long(OPT_COMPRESS_PROG)
+                .help("compress temporary files with PROG, decompress with PROG -d")
+                .long_help("PROG has to take input from stdin and output to stdout")
+                .value_name("PROG")
+        )
+        .arg(
+            Arg::with_name(OPT_BATCH_SIZE)
+                .long(OPT_BATCH_SIZE)
+                .help("Merge at most N_MERGE inputs at once.")
+                .value_name("N_MERGE")
+        )
         .arg(
             Arg::with_name(OPT_FILES0_FROM)
                 .long(OPT_FILES0_FROM)
@@ -1165,6 +1184,14 @@ pub fn uumain(args: impl uucore::Args) -> i32 {
         .map(PathBuf::from)
         .unwrap_or_else(env::temp_dir);
 
+    settings.compress_prog = matches.value_of(OPT_COMPRESS_PROG).map(String::from);
+
+    if let Some(n_merge) = matches.value_of(OPT_BATCH_SIZE) {
+        settings.merge_batch_size = n_merge
+            .parse()
+            .unwrap_or_else(|_| crash!(2, "invalid --batch-size argument '{}'", n_merge));
+    }
+
     settings.zero_terminated = matches.is_present(OPT_ZERO_TERMINATED);
     settings.merge = matches.is_present(OPT_MERGE);
 
@@ -1230,17 +1257,17 @@ 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);
     }
 }
 
 fn exec(files: &[String], settings: &GlobalSettings) -> i32 {
     if settings.merge {
-        let mut file_merger = merge::merge(files, settings);
+        let mut file_merger = merge::merge_with_file_limit(files.iter().map(open), settings);
         file_merger.write_all(settings);
     } else if settings.check {
         if files.len() > 1 {
@@ -1250,16 +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))
     }
 }
 
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/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..5baff4825 100644
--- a/src/uu/stdbuf/src/stdbuf.rs
+++ b/src/uu/stdbuf/src/stdbuf.rs
@@ -69,9 +69,9 @@ 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)?,
         })
     }
 }
diff --git a/src/uu/timeout/Cargo.toml b/src/uu/timeout/Cargo.toml
index 206a98c08..d16559858 100644
--- a/src/uu/timeout/Cargo.toml
+++ b/src/uu/timeout/Cargo.toml
@@ -16,7 +16,6 @@ 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_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/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/uucore/src/lib/features/entries.rs b/src/uucore/src/lib/features/entries.rs
index d2dce2461..477fac470 100644
--- a/src/uucore/src/lib/features/entries.rs
+++ b/src/uucore/src/lib/features/entries.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 (vars) Passwd cstr fnam gecos ngroups
+// spell-checker:ignore (vars) Passwd cstr fnam gecos ngroups egid
 
 //! Get password/group file entry
 //!
@@ -72,6 +72,45 @@ pub fn get_groups() -> IOResult<Vec<gid_t>> {
     }
 }
 
+/// The list of group IDs returned from GNU's `groups` and GNU's `id --groups`
+/// starts with the effective group ID (egid).
+/// This is a wrapper for `get_groups()` to mimic this behavior.
+///
+/// If `arg_id` is `None` (default), `get_groups_gnu` moves the effective
+/// group id (egid) to the first entry in the returned Vector.
+/// If `arg_id` is `Some(x)`, `get_groups_gnu` moves the id with value `x`
+/// to the first entry in the returned Vector. This might be necessary
+/// for `id --groups --real` if `gid` and `egid` are not equal.
+///
+/// From: https://www.man7.org/linux/man-pages/man3/getgroups.3p.html
+/// As implied by the definition of supplementary groups, the
+/// effective group ID may appear in the array returned by
+/// getgroups() or it may be returned only by getegid().  Duplication
+/// may exist, but the application needs to call getegid() to be sure
+/// of getting all of the information. Various implementation
+/// variations and administrative sequences cause the set of groups
+/// appearing in the result of getgroups() to vary in order and as to
+/// whether the effective group ID is included, even when the set of
+/// 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 groups = get_groups()?;
+    let egid = arg_id.unwrap_or_else(crate::features::process::getegid);
+    Ok(sort_groups(groups, egid))
+}
+
+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
+}
+
+#[derive(Copy, Clone)]
 pub struct Passwd {
     inner: passwd,
 }
@@ -268,3 +307,27 @@ pub fn usr2uid(name: &str) -> IOResult<uid_t> {
 pub fn grp2gid(name: &str) -> IOResult<gid_t> {
     Group::locate(name).map(|p| p.gid())
 }
+
+#[cfg(test)]
+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() {
+            if let Some(last) = groups.pop() {
+                groups.insert(0, last);
+                assert_eq!(get_groups_gnu(Some(last)).unwrap(), groups);
+            }
+        }
+    }
+}
diff --git a/src/uucore/src/lib/features/fs.rs b/src/uucore/src/lib/features/fs.rs
index 38cdbef94..525f305e3 100644
--- a/src/uucore/src/lib/features/fs.rs
+++ b/src/uucore/src/lib/features/fs.rs
@@ -225,51 +225,6 @@ pub fn canonicalize<P: AsRef<Path>>(original: P, can_mode: CanonicalizeMode) ->
     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/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/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_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_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 cee13bdc3..c1b98aea1 100644
--- a/tests/by-util/test_groups.rs
+++ b/tests/by-util/test_groups.rs
@@ -1,41 +1,56 @@
 use crate::common::util::*;
 
 #[test]
+#[cfg(unix)]
 fn test_groups() {
-    let result = new_ucmd!().run();
-    println!("result.stdout = {}", result.stdout_str());
-    println!("result.stderr = {}", result.stderr_str());
-    if is_ci() && result.stdout_str().trim().is_empty() {
-        // In the CI, some server are failing to return the group.
-        // As seems to be a configuration issue, ignoring it
-        return;
+    if !is_ci() {
+        new_ucmd!().succeeds().stdout_is(expected_result(&[]));
+    } else {
+        // TODO: investigate how this could be tested in CI
+        // stderr = groups: cannot find name for group ID 116
+        println!("test skipped:");
     }
-    result.success();
-    assert!(!result.stdout_str().trim().is_empty());
 }
 
 #[test]
-fn test_groups_arg() {
-    // get the username with the "id -un" command
-    let result = TestScenario::new("id").ucmd_keepenv().arg("-un").run();
-    println!("result.stdout = {}", result.stdout_str());
-    println!("result.stderr = {}", result.stderr_str());
-    let s1 = String::from(result.stdout_str().trim());
-    if is_ci() && s1.parse::<f64>().is_ok() {
-        // In the CI, some server are failing to return id -un.
-        // So, if we are getting a uid, just skip this test
-        // As seems to be a configuration issue, ignoring it
+#[cfg(unix)]
+#[ignore = "fixme: 'groups USERNAME' needs more debugging"]
+fn test_groups_username() {
+    let scene = TestScenario::new(util_name!());
+    let whoami_result = scene.cmd("whoami").run();
+
+    let username = if whoami_result.succeeded() {
+        whoami_result.stdout_move_str()
+    } else if is_ci() {
+        String::from("docker")
+    } else {
+        println!("test skipped:");
         return;
-    }
+    };
 
-    println!("result.stdout = {}", result.stdout_str());
-    println!("result.stderr = {}", result.stderr_str());
-    result.success();
-    assert!(!result.stdout_str().is_empty());
-    let username = result.stdout_str().trim();
+    // TODO: stdout should be in the form: "username : group1 group2 group3"
 
-    // call groups with the user name to check that we
-    // are getting something
-    new_ucmd!().arg(username).succeeds();
-    assert!(!result.stdout_str().is_empty());
+    scene
+        .ucmd()
+        .arg(&username)
+        .succeeds()
+        .stdout_is(expected_result(&[&username]));
+}
+
+#[cfg(unix)]
+fn expected_result(args: &[&str]) -> String {
+    // 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)
+        .cmd_keepenv(util_name)
+        .env("LANGUAGE", "C")
+        .args(args)
+        .args(&["-Gn"])
+        .succeeds()
+        .stdout_move_str()
 }
diff --git a/tests/by-util/test_id.rs b/tests/by-util/test_id.rs
index 1f8249aab..c3a08810a 100644
--- a/tests/by-util/test_id.rs
+++ b/tests/by-util/test_id.rs
@@ -104,19 +104,23 @@ fn test_id_group() {
 }
 
 #[test]
+#[cfg(any(target_vendor = "apple", target_os = "linux"))]
 fn test_id_groups() {
     let scene = TestScenario::new(util_name!());
-
-    let result = scene.ucmd().arg("-G").succeeds();
-    let groups = result.stdout_str().trim().split_whitespace();
-    for s in groups {
-        assert!(s.parse::<f64>().is_ok());
-    }
-
-    let result = scene.ucmd().arg("--groups").succeeds();
-    let groups = result.stdout_str().trim().split_whitespace();
-    for s in groups {
-        assert!(s.parse::<f64>().is_ok());
+    for g_flag in &["-G", "--groups"] {
+        scene
+            .ucmd()
+            .arg(g_flag)
+            .succeeds()
+            .stdout_is(expected_result(&[g_flag], false));
+        for &r_flag in &["-r", "--real"] {
+            let args = [g_flag, r_flag];
+            scene
+                .ucmd()
+                .args(&args)
+                .succeeds()
+                .stdout_is(expected_result(&args, false));
+        }
     }
 }
 
@@ -167,3 +171,32 @@ fn test_id_password_style() {
 
     assert!(result.stdout_str().starts_with(&username));
 }
+
+#[cfg(any(target_vendor = "apple", target_os = "linux"))]
+fn expected_result(args: &[&str], exp_fail: bool) -> String {
+    #[cfg(target_os = "linux")]
+    let util_name = util_name!();
+    #[cfg(target_vendor = "apple")]
+    let util_name = format!("g{}", util_name!());
+
+    let result = if !exp_fail {
+        TestScenario::new(&util_name)
+            .cmd_keepenv(util_name)
+            .env("LANGUAGE", "C")
+            .args(args)
+            .succeeds()
+            .stdout_move_str()
+    } else {
+        TestScenario::new(&util_name)
+            .cmd_keepenv(util_name)
+            .env("LANGUAGE", "C")
+            .args(args)
+            .fails()
+            .stderr_move_str()
+    };
+    return if cfg!(target_os = "macos") && result.starts_with("gid") {
+        result[1..].to_string()
+    } else {
+        result
+    };
+}
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_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 02636b027..7a0143b43 100644
--- a/tests/by-util/test_sort.rs
+++ b/tests/by-util/test_sort.rs
@@ -792,3 +792,59 @@ fn test_nonexistent_file() {
 fn test_blanks() {
     test_helper("blanks", &["-b", "--ignore-blanks"]);
 }
+
+#[test]
+fn sort_multiple() {
+    new_ucmd!()
+        .args(&["no_trailing_newline1.txt", "no_trailing_newline2.txt"])
+        .succeeds()
+        .stdout_is("a\nb\nb\n");
+}
+
+#[test]
+fn sort_empty_chunk() {
+    new_ucmd!()
+        .args(&["-S", "40B"])
+        .pipe_in("a\na\n")
+        .succeeds()
+        .stdout_is("a\na\n");
+}
+
+#[test]
+#[cfg(target_os = "linux")]
+fn test_compress() {
+    new_ucmd!()
+        .args(&[
+            "ext_sort.txt",
+            "-n",
+            "--compress-program",
+            "gzip",
+            "-S",
+            "10",
+        ])
+        .succeeds()
+        .stdout_only_fixture("ext_sort.expected");
+}
+
+#[test]
+fn test_compress_fail() {
+    new_ucmd!()
+        .args(&[
+            "ext_sort.txt",
+            "-n",
+            "--compress-program",
+            "nonexistent-program",
+            "-S",
+            "10",
+        ])
+        .fails()
+        .stderr_only("sort: couldn't execute compress program: errno 2");
+}
+
+#[test]
+fn test_merge_batches() {
+    new_ucmd!()
+        .args(&["ext_sort.txt", "-n", "-S", "150B"])
+        .succeeds()
+        .stdout_only_fixture("ext_sort.expected");
+}
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_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 2f7d7dcc4..11425e9b8 100644
--- a/tests/common/util.rs
+++ b/tests/common/util.rs
@@ -625,11 +625,20 @@ 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/sort/no_trailing_newline1.txt b/tests/fixtures/sort/no_trailing_newline1.txt
new file mode 100644
index 000000000..0a207c060
--- /dev/null
+++ b/tests/fixtures/sort/no_trailing_newline1.txt
@@ -0,0 +1,2 @@
+a
+b
\ No newline at end of file
diff --git a/tests/fixtures/sort/no_trailing_newline2.txt b/tests/fixtures/sort/no_trailing_newline2.txt
new file mode 100644
index 000000000..63d8dbd40
--- /dev/null
+++ b/tests/fixtures/sort/no_trailing_newline2.txt
@@ -0,0 +1 @@
+b
\ No newline at end of file
diff --git a/util/build-gnu.sh b/util/build-gnu.sh
index 83136e733..44ecd2044 100644
--- a/util/build-gnu.sh
+++ b/util/build-gnu.sh
@@ -1,6 +1,6 @@
 #!/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
@@ -116,4 +116,6 @@ sed -i -e "s|rm: cannot remove directory 'b/a/p'|rm: cannot remove 'b'|g" tests/
 
 sed -i -e "s|rm: cannot remove 'a/1'|rm: cannot remove 'a'|g" tests/rm/rm2.sh
 
+sed -i -e "s|removed directory 'a/'|removed directory 'a'|g" tests/rm/v-slash.sh
+
 test -f "${BUILDDIR}/getlimits" || cp src/getlimits "${BUILDDIR}"