Merge branch 'main' into core-1

Author: oech3

src/uu/tail/src/tail.rs

@@ -470,7 +470,7 @@ fn bounded_tail(file: &mut File, settings: &Settings) {
             file.seek(SeekFrom::Start(i as u64)).unwrap();
         }
         FilterMode::Lines(Signum::MinusZero, _) => {
-            return;
+            file.seek(SeekFrom::End(0)).unwrap();
         }
         FilterMode::Bytes(Signum::Negative(count)) => {
             if file.seek(SeekFrom::End(-(*count as i64))).is_err() {
@@ -484,7 +484,7 @@ fn bounded_tail(file: &mut File, settings: &Settings) {
             file.seek(SeekFrom::Start(*count - 1)).unwrap();
         }
         FilterMode::Bytes(Signum::MinusZero) => {
-            return;
+            file.seek(SeekFrom::End(0)).unwrap();
         }
         _ => {}
     }
@@ -524,6 +524,11 @@ fn unbounded_tail<T: Read>(reader: &mut BufReader<T>, settings: &Settings) -> UR
             chunks.fill(reader)?;
             chunks.print(&mut writer)?;
         }
+        FilterMode::Lines(Signum::MinusZero, sep) => {
+            let mut chunks = chunks::LinesChunkBuffer::new(*sep, 0);
+            chunks.fill(reader)?;
+            chunks.print(&mut writer)?;
+        }
         FilterMode::Bytes(Signum::PlusZero | Signum::Positive(1)) => {
             io::copy(reader, &mut writer)?;
         }

src/uu/timeout/src/timeout.rs

@@ -270,7 +270,14 @@ fn wait_or_kill_process(
     match process.wait_or_timeout(duration, None) {
         Ok(Some(status)) => {
             if preserve_status {
-                Ok(status.code().unwrap_or_else(|| status.signal().unwrap()))
+                let exit_code = status.code().unwrap_or_else(|| {
+                    status.signal().unwrap_or_else(|| {
+                        // Extremely rare: process exited but we have neither exit code nor signal.
+                        // This can happen on some platforms or in unusual termination scenarios.
+                        ExitStatus::TimeoutFailed.into()
+                    })
+                });
+                Ok(exit_code)
             } else {
                 Ok(ExitStatus::TimeoutFailed.into())
             }
@@ -358,10 +365,14 @@ fn timeout(
     // structure of `wait_or_kill_process()`. They can probably be
     // refactored into some common function.
     match process.wait_or_timeout(duration, Some(&SIGNALED)) {
-        Ok(Some(status)) => Err(status
-            .code()
-            .unwrap_or_else(|| preserve_signal_info(status.signal().unwrap()))
-            .into()),
+        Ok(Some(status)) => {
+            let exit_code = status.code().unwrap_or_else(|| {
+                status
+                    .signal()
+                    .map_or_else(|| ExitStatus::TimeoutFailed.into(), preserve_signal_info)
+            });
+            Err(exit_code.into())
+        }
         Ok(None) => {
             report_if_verbose(signal, &cmd[0], verbose);
             send_signal(process, signal, foreground);

tests/by-util/test_tail.rs

@@ -233,6 +233,28 @@ fn test_nc_0_wo_follow2() {
         .no_output();
 }
 
+#[test]
+#[cfg(not(target_os = "windows"))]
+fn test_n0_with_follow() {
+    let (at, mut ucmd) = at_and_ucmd!();
+    let test_file = "test.txt";
+    // Create file with multiple lines
+    at.write(test_file, "line1\nline2\nline3\n");
+
+    let mut child = ucmd.arg("-n0").arg("-f").arg(test_file).run_no_wait();
+    child.make_assertion_with_delay(500).is_alive();
+
+    // Append a new line
+    at.append(test_file, "new\n");
+
+    // Should only print the newly appended line
+    child
+        .make_assertion_with_delay(DEFAULT_SLEEP_INTERVAL_MILLIS)
+        .with_current_output()
+        .stdout_only("new\n");
+    child.kill();
+}
+
 // TODO: Add similar test for windows
 #[test]
 #[cfg(unix)]