date -d supports - 1 year ago, 2 second, etc

Cargo.lock

@@ -2538,7 +2538,9 @@ version = "0.0.18"
 dependencies = [
  "chrono",
  "clap",
+ "humantime_to_duration",
  "libc",
+ "time",
  "uucore",
  "windows-sys 0.45.0",
 ]

src/uu/date/Cargo.toml

@@ -1,3 +1,4 @@
+# spell-checker:ignore humantime
 [package]
 name = "uu_date"
 version = "0.0.18"
@@ -16,8 +17,11 @@ path = "src/date.rs"
 
 [dependencies]
 chrono = { workspace=true }
+#/ TODO: check if we can avoid chrono+time
+time = { workspace=true }
 clap = { workspace=true }
 uucore = { workspace=true }
+humantime_to_duration = { workspace=true }
 
 [target.'cfg(unix)'.dependencies]
 libc = { workspace=true }

src/uu/date/src/date.rs

@@ -6,10 +6,10 @@
 // For the full copyright and license information, please view the LICENSE
 // file that was distributed with this source code.
 
-// spell-checker:ignore (chrono) Datelike Timelike ; (format) DATEFILE MMDDhhmm ; (vars) datetime datetimes
+// spell-checker:ignore (chrono) Datelike Timelike ; (format) DATEFILE MMDDhhmm ; (vars) datetime datetimes humantime
 
 use chrono::format::{Item, StrftimeItems};
-use chrono::{DateTime, FixedOffset, Local, Offset, Utc};
+use chrono::{DateTime, Duration as ChronoDuration, FixedOffset, Local, Offset, Utc};
 #[cfg(windows)]
 use chrono::{Datelike, Timelike};
 use clap::{crate_version, Arg, ArgAction, Command};
@@ -18,6 +18,7 @@ use libc::{clock_settime, timespec, CLOCK_REALTIME};
 use std::fs::File;
 use std::io::{BufRead, BufReader};
 use std::path::PathBuf;
+use time::Duration;
 use uucore::display::Quotable;
 #[cfg(not(any(target_os = "redox")))]
 use uucore::error::FromIo;
@@ -96,6 +97,7 @@ enum DateSource {
     Now,
     Custom(String),
     File(PathBuf),
+    Human(Duration),
 }
 
 enum Iso8601Format {
@@ -168,7 +170,11 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
     };
 
     let date_source = if let Some(date) = matches.get_one::<String>(OPT_DATE) {
-        DateSource::Custom(date.into())
+        if let Ok(duration) = humantime_to_duration::from_str(date.as_str()) {
+            DateSource::Human(duration)
+        } else {
+            DateSource::Custom(date.into())
+        }
     } else if let Some(file) = matches.get_one::<String>(OPT_FILE) {
         DateSource::File(file.into())
     } else {
@@ -219,6 +225,15 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
                 let iter = std::iter::once(date);
                 Box::new(iter)
             }
+            DateSource::Human(ref input) => {
+                // Get the current DateTime<FixedOffset> and convert the input time::Duration to chrono::Duration
+                // for things like "1 year ago"
+                let current_time = DateTime::<FixedOffset>::from(Local::now());
+                let input_chrono = ChronoDuration::seconds(input.as_seconds_f32() as i64)
+                    + ChronoDuration::nanoseconds(input.subsec_nanoseconds() as i64);
+                let iter = std::iter::once(Ok(current_time + input_chrono));
+                Box::new(iter)
+            }
             DateSource::File(ref path) => {
                 if path.is_dir() {
                     return Err(USimpleError::new(

tests/by-util/test_date.rs

@@ -334,6 +334,29 @@ fn test_invalid_format_string() {
     assert!(result.stderr_str().starts_with("date: invalid format "));
 }
 
+#[test]
+fn test_date_string_human() {
+    let date_formats = vec![
+        "1 year ago",
+        "1 year",
+        "2 months ago",
+        "15 days ago",
+        "1 week ago",
+        "5 hours ago",
+        "30 minutes ago",
+        "10 seconds",
+    ];
+    let re = Regex::new(r"^\d{4}-\d{2}-\d{2} \d{2}:\d{2}\n$").unwrap();
+    for date_format in date_formats {
+        new_ucmd!()
+            .arg("-d")
+            .arg(date_format)
+            .arg("+%Y-%m-%d %S:%M")
+            .succeeds()
+            .stdout_matches(&re);
+    }
+}
+
 #[test]
 fn test_invalid_date_string() {
     new_ucmd!()