From 6c1da2802d626632bdcf370ba013da1c9adc2260 Mon Sep 17 00:00:00 2001
From: Saadanjum0 <160885369+Saadanjum0@users.noreply.github.com>
Date: Thu, 1 Oct 2026 16:19:39 +0500
Subject: [PATCH] Refuse watch mode when stdout is not a terminal

Previously 'procs -w | cat' streamed ANSI screen frames into the pipe forever. Now it exits with an error, like top and watch do. Plain output piping is unchanged. Refs #982.
---
 src/main.rs | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/src/main.rs b/src/main.rs
index 9a51b686d..38e29b821 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -204,7 +204,15 @@ fn run_list() {
     }
 }
 
+fn check_watch_tty(is_tty: bool) -> Result<(), Error> {
+    if !is_tty {
+        anyhow::bail!("--watch requires a terminal, but stdout is not a TTY");
+    }
+    Ok(())
+}
+
 fn run_watch(opt: &mut Opt, config: &Config, interval: u64) -> Result<(), Error> {
+    check_watch_tty(Term::stdout().is_term())?;
     Watcher::start(opt, config, interval)
 }
 
@@ -310,6 +318,12 @@ mod tests {
         assert!(ret.is_ok());
     }
 
+    #[test]
+    fn test_watch_requires_tty() {
+        assert!(check_watch_tty(false).is_err());
+        assert!(check_watch_tty(true).is_ok());
+    }
+
     #[test]
     fn test_run_gen_config() {
         let ret = run_gen_config();