Add support for @%s time format

3 files changed, 38 insertions, 5 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 08f447f..1717b85 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,7 @@
 ## Features
 
 - Add `dir` as an alias to `directory` when using `-t` \ `--type`, see #1460 and #1464 (@Ato2207).
+- Add support for @%s date format in time filters similar to GNU date (seconds since Unix epoch for --older/--newer), see #1493 (@nabellows)
 
 ## Bugfixes
 
diff --git a/doc/fd.1 b/doc/fd.1
index 8877317..1ac63c5 100644
--- a/doc/fd.1
+++ b/doc/fd.1
@@ -312,8 +312,9 @@ tebibytes
 Filter results based on the file modification time.
 Files with modification times greater than the argument will be returned.
 The argument can be provided as a duration (\fI10h, 1d, 35min\fR) or as a specific point
-in time in either full RFC3339 format with time zone, or as a date or datetime in the
-local time zone (\fIYYYY-MM-DD\fR or \fIYYYY-MM-DD HH:MM:SS\fR).
+in time as full RFC3339 format with time zone, as a date or datetime in the
+local time zone (\fIYYYY-MM-DD\fR or \fIYYYY-MM-DD HH:MM:SS\fR), or as the prefix '@'
+followed by the number of seconds since the Unix epoch (@[0-9]+).
 \fB\-\-change-newer-than\fR,
 .B --newer
 or
@@ -324,13 +325,15 @@ Examples:
   \-\-changed-within 2weeks
   \-\-change-newer-than "2018-10-27 10:00:00"
   \-\-newer 2018-10-27
+  \-\-changed-after @1704067200
 .TP
 .BI "\-\-changed-before " date|duration
 Filter results based on the file modification time.
 Files with modification times less than the argument will be returned.
 The argument can be provided as a duration (\fI10h, 1d, 35min\fR) or as a specific point
-in time in either full RFC3339 format with time zone, or as a date or datetime in the
-local time zone (\fIYYYY-MM-DD\fR or \fIYYYY-MM-DD HH:MM:SS\fR).
+in time as full RFC3339 format with time zone, as a date or datetime in the
+local time zone (\fIYYYY-MM-DD\fR or \fIYYYY-MM-DD HH:MM:SS\fR), or as the prefix '@'
+followed by the number of seconds since the Unix epoch (@[0-9]+).
 .B --change-older-than
 or
 .B --older
@@ -339,6 +342,7 @@ can be used as aliases.
 Examples:
   \-\-changed-before "2018-10-27 10:00:00"
   \-\-change-older-than 2weeks
+  \-\-older @1704067200
 .TP
 .BI "-o, \-\-owner " [user][:group]
 Filter files by their user and/or group. Format: [(user|uid)][:(group|gid)]. Either side
diff --git a/src/filter/time.rs b/src/filter/time.rs
index 0070e5e..9631f13 100644
--- a/src/filter/time.rs
+++ b/src/filter/time.rs
@@ -1,4 +1,4 @@
-use chrono::{DateTime, Local, NaiveDate, NaiveDateTime};
+use chrono::{DateTime, Local, NaiveDate, NaiveDateTime, Utc};
 
 use std::time::SystemTime;
 
@@ -31,6 +31,13 @@ impl TimeFilter {
                             .and_local_timezone(Local)
                             .latest()
                     })
+                    .or_else(|| {
+                        let timestamp_secs = s.strip_prefix('@')?.parse().ok()?;
+                        NaiveDateTime::from_timestamp_opt(timestamp_secs, 0)?
+                            .and_local_timezone(Utc)
+                            .latest()
+                            .map(Into::into)
+                    })
                     .map(|dt| dt.into())
             })
     }
@@ -135,5 +142,26 @@ mod tests {
         assert!(!TimeFilter::after(&ref_time, t10s_before)
             .unwrap()
             .applies_to(&t1m_ago));
+
+        let ref_timestamp = 1707723412u64; // Mon Feb 12 07:36:52 UTC 2024
+        let ref_time = DateTime::parse_from_rfc3339("2024-02-12T07:36:52+00:00")
+            .unwrap()
+            .into();
+        let t1m_ago = ref_time - Duration::from_secs(60);
+        let t1s_later = ref_time + Duration::from_secs(1);
+        // Timestamp only supported via '@' prefix
+        assert!(TimeFilter::before(&ref_time, &ref_timestamp.to_string()).is_none());
+        assert!(TimeFilter::before(&ref_time, &format!("@{}", ref_timestamp))
+            .unwrap()
+            .applies_to(&t1m_ago));
+        assert!(!TimeFilter::before(&ref_time, &format!("@{}", ref_timestamp))
+            .unwrap()
+            .applies_to(&t1s_later));
+        assert!(!TimeFilter::after(&ref_time, &format!("@{}", ref_timestamp))
+            .unwrap()
+            .applies_to(&t1m_ago));
+        assert!(TimeFilter::after(&ref_time, &format!("@{}", ref_timestamp))
+            .unwrap()
+            .applies_to(&t1s_later));
     }
 }