From 820e804f8afc235dd36254c5f70a4663036cb811 Mon Sep 17 00:00:00 2001
From: mattsu <matsui.atsushi.home@gmail.com>
Date: Mon, 24 Nov 2025 14:19:13 +0900
Subject: [PATCH 1/3] fix(seq): handle BrokenPipe like GNU

---
 src/uu/seq/src/seq.rs | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/uu/seq/src/seq.rs b/src/uu/seq/src/seq.rs
index 6741356606d..7b56c26f574 100644
--- a/src/uu/seq/src/seq.rs
+++ b/src/uu/seq/src/seq.rs
@@ -4,7 +4,7 @@
 // file that was distributed with this source code.
 // spell-checker:ignore (ToDO) bigdecimal extendedbigdecimal numberparse hexadecimalfloat biguint
 use std::ffi::{OsStr, OsString};
-use std::io::{BufWriter, ErrorKind, Write, stdout};
+use std::io::{BufWriter, Write, stdout};
 
 use clap::{Arg, ArgAction, Command};
 use num_bigint::BigUint;
@@ -211,7 +211,12 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
 
     match result {
         Ok(()) => Ok(()),
-        Err(err) if err.kind() == ErrorKind::BrokenPipe => Ok(()),
+        Err(err) if err.kind() == std::io::ErrorKind::BrokenPipe => {
+            // GNU seq prints the Broken pipe message but still exits with status 0
+            let err = err.map_err_context(|| "write error".into());
+            uucore::show_error!("{err}");
+            Ok(())
+        }
         Err(err) => Err(err.map_err_context(|| "write error".into())),
     }
 }

From 1d99af28ecc73295421033ea5e77bef0ecc1e568 Mon Sep 17 00:00:00 2001
From: mattsu <matsui.atsushi.home@gmail.com>
Date: Wed, 26 Nov 2025 16:20:39 +0900
Subject: [PATCH 2/3] test: add Unix-specific test for seq command broken pipe
 handling

- Ensures seq exits gracefully with code 0 and reports "Broken pipe" error on stderr when stdout pipe is prematurely closed
- Validates correct behavior for common scenario where output is piped to commands like head that terminate early
---
 tests/by-util/test_seq.rs | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/tests/by-util/test_seq.rs b/tests/by-util/test_seq.rs
index f82a6228fe1..238f634c8d0 100644
--- a/tests/by-util/test_seq.rs
+++ b/tests/by-util/test_seq.rs
@@ -10,6 +10,25 @@ fn test_invalid_arg() {
     new_ucmd!().arg("--definitely-invalid").fails_with_code(1);
 }
 
+#[test]
+#[cfg(unix)]
+fn test_broken_pipe_still_exits_success() {
+    use std::process::Stdio;
+
+    let mut child = new_ucmd!()
+        .args(&["1", "5"])
+        .set_stdout(Stdio::piped())
+        .run_no_wait();
+
+    // 出力先が先に閉じられたパイプへ書こうとして Broken pipe を発生させる。
+    child.close_stdout();
+    let result = child.wait().unwrap();
+
+    result
+        .code_is(0)
+        .stderr_contains("write error: Broken pipe");
+}
+
 #[test]
 fn test_no_args() {
     new_ucmd!()

From f9a517bcd0f106db058e8029d396acf9b0156ac1 Mon Sep 17 00:00:00 2001
From: mattsu <matsui.atsushi.home@gmail.com>
Date: Wed, 26 Nov 2025 20:06:24 +0900
Subject: [PATCH 3/3] refactor(test): translate Japanese comment to English in
 test_seq.rs

- Updated a comment in the test for broken pipe behavior to use English instead of Japanese, enhancing readability for non-Japanese speakers and aligning with project standards. No functional changes to the test logic.
---
 tests/by-util/test_seq.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/by-util/test_seq.rs b/tests/by-util/test_seq.rs
index 238f634c8d0..de0ad10d9fb 100644
--- a/tests/by-util/test_seq.rs
+++ b/tests/by-util/test_seq.rs
@@ -20,7 +20,7 @@ fn test_broken_pipe_still_exits_success() {
         .set_stdout(Stdio::piped())
         .run_no_wait();
 
-    // 出力先が先に閉じられたパイプへ書こうとして Broken pipe を発生させる。
+    // Trigger a Broken pipe by writing to a pipe whose reader closed first.
     child.close_stdout();
     let result = child.wait().unwrap();