From c9be787fc92d3d7ae4b97a4d326f12850c035627 Mon Sep 17 00:00:00 2001
From: Quin Gillespie <trypsynth@gmail.com>
Date: Mon, 12 Jan 2026 21:31:12 -0700
Subject: [PATCH 1/3] Fixed passing -0 to tail. Closes #10191

---
 src/uu/tail/src/tail.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/uu/tail/src/tail.rs b/src/uu/tail/src/tail.rs
index 3a16f670b63..4e570d0676e 100644
--- a/src/uu/tail/src/tail.rs
+++ b/src/uu/tail/src/tail.rs
@@ -403,6 +403,10 @@ fn forwards_thru_file(
 /// `num_delimiters` instance of `delimiter`. The `file` is left seek'd to the
 /// position just after that delimiter.
 fn backwards_thru_file(file: &mut File, num_delimiters: u64, delimiter: u8) {
+    if num_delimiters == 0 {
+        file.seek(SeekFrom::End(0)).unwrap();
+        return;
+    }
     // This variable counts the number of delimiters found in the file
     // so far (reading from the end of the file toward the beginning).
     let mut counter = 0;

From 1894e4364386ff816f08f4ec460d63c5b73eefdf Mon Sep 17 00:00:00 2001
From: Quin Gillespie <trypsynth@gmail.com>
Date: Thu, 15 Jan 2026 08:51:23 -0700
Subject: [PATCH 2/3] Added a test

---
 src/uu/tail/src/tail.rs | 35 +++++++++++++++++++++++++++++++++--
 1 file changed, 33 insertions(+), 2 deletions(-)

diff --git a/src/uu/tail/src/tail.rs b/src/uu/tail/src/tail.rs
index 4e570d0676e..fdbe82ccf97 100644
--- a/src/uu/tail/src/tail.rs
+++ b/src/uu/tail/src/tail.rs
@@ -575,8 +575,28 @@ where
 #[cfg(test)]
 mod tests {
 
-    use crate::forwards_thru_file;
-    use std::io::Cursor;
+    use crate::{backwards_thru_file, forwards_thru_file};
+    use std::{
+        env,
+        fs::{self, File},
+        io::{Cursor, Seek, SeekFrom, Write},
+        process,
+        time::{SystemTime, UNIX_EPOCH},
+    };
+
+    fn create_temp_file(contents: &[u8]) -> (std::path::PathBuf, File) {
+        let mut path = env::temp_dir();
+        let unique = SystemTime::now()
+            .duration_since(UNIX_EPOCH)
+            .unwrap()
+            .as_nanos();
+        path.push(format!("uutils-tail-test-{}-{unique}", process::id()));
+        let mut file = File::create(&path).unwrap();
+        file.write_all(contents).unwrap();
+        file.flush().unwrap();
+        file.seek(SeekFrom::Start(0)).unwrap();
+        (path, file)
+    }
 
     #[test]
     fn test_forwards_thru_file_zero() {
@@ -599,4 +619,15 @@ mod tests {
         let i = forwards_thru_file(&mut reader, 2, b'\n').unwrap();
         assert_eq!(i, 2);
     }
+
+    #[test]
+    fn test_backwards_thru_file_zero() {
+        let (path, mut file) = create_temp_file(b"a\nb\nc\n");
+        let len = file.metadata().unwrap().len();
+        backwards_thru_file(&mut file, 0, b'\n');
+        let pos = file.seek(SeekFrom::Current(0)).unwrap();
+        assert_eq!(pos, len);
+        drop(file);
+        fs::remove_file(path).unwrap();
+    }
 }

From 66a1944d7edb930a9ed4e96a56a3e55b2fc7771d Mon Sep 17 00:00:00 2001
From: Quin Gillespie <trypsynth@gmail.com>
Date: Fri, 16 Jan 2026 22:46:43 -0700
Subject: [PATCH 3/3] Fix test

---
 src/uu/tail/src/tail.rs    | 35 ++---------------------------------
 tests/by-util/test_tail.rs | 10 ++++++++++
 2 files changed, 12 insertions(+), 33 deletions(-)

diff --git a/src/uu/tail/src/tail.rs b/src/uu/tail/src/tail.rs
index fdbe82ccf97..4e570d0676e 100644
--- a/src/uu/tail/src/tail.rs
+++ b/src/uu/tail/src/tail.rs
@@ -575,28 +575,8 @@ where
 #[cfg(test)]
 mod tests {
 
-    use crate::{backwards_thru_file, forwards_thru_file};
-    use std::{
-        env,
-        fs::{self, File},
-        io::{Cursor, Seek, SeekFrom, Write},
-        process,
-        time::{SystemTime, UNIX_EPOCH},
-    };
-
-    fn create_temp_file(contents: &[u8]) -> (std::path::PathBuf, File) {
-        let mut path = env::temp_dir();
-        let unique = SystemTime::now()
-            .duration_since(UNIX_EPOCH)
-            .unwrap()
-            .as_nanos();
-        path.push(format!("uutils-tail-test-{}-{unique}", process::id()));
-        let mut file = File::create(&path).unwrap();
-        file.write_all(contents).unwrap();
-        file.flush().unwrap();
-        file.seek(SeekFrom::Start(0)).unwrap();
-        (path, file)
-    }
+    use crate::forwards_thru_file;
+    use std::io::Cursor;
 
     #[test]
     fn test_forwards_thru_file_zero() {
@@ -619,15 +599,4 @@ mod tests {
         let i = forwards_thru_file(&mut reader, 2, b'\n').unwrap();
         assert_eq!(i, 2);
     }
-
-    #[test]
-    fn test_backwards_thru_file_zero() {
-        let (path, mut file) = create_temp_file(b"a\nb\nc\n");
-        let len = file.metadata().unwrap().len();
-        backwards_thru_file(&mut file, 0, b'\n');
-        let pos = file.seek(SeekFrom::Current(0)).unwrap();
-        assert_eq!(pos, len);
-        drop(file);
-        fs::remove_file(path).unwrap();
-    }
 }
diff --git a/tests/by-util/test_tail.rs b/tests/by-util/test_tail.rs
index 3dd0ee0d2d4..3def2eb08a4 100644
--- a/tests/by-util/test_tail.rs
+++ b/tests/by-util/test_tail.rs
@@ -1125,6 +1125,16 @@ fn test_obsolete_syntax_small_file() {
         .stdout_is("a\nb\nc\nd\ne\n");
 }
 
+/// Test for obsolete syntax `tail -0 FILE`: print nothing and exit cleanly.
+#[test]
+fn test_obsolete_syntax_zero_lines_file() {
+    new_ucmd!()
+        .args(&["-0", "foobar.txt"])
+        .succeeds()
+        .no_stderr()
+        .no_stdout();
+}
+
 /// Test for reading all lines, specified by `tail -n +0`.
 #[test]
 fn test_positive_zero_lines() {