fix(seq): handle BrokenPipe like GNU

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())),
     }
 }

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();
+
+    // Trigger a Broken pipe by writing to a pipe whose reader closed first.
+    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!()