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Killing processes safely

How MacPeek ends a process from PortPeek, FileLockPeek or ProcessPeek: revalidation, SIGTERM first, release verification and an explicit force kill.

Updated

Killing the wrong process is worse than not killing one, so MacPeek never signals a stale PID. PortPeek, FileLockPeek and ProcessPeek all use this same shared safety logic; the steps below describe it from PortPeek, and the table at the end shows what each utility verifies.

The sequence

  1. Re-scan the port when you click Kill.
  2. Confirm the port still exists and the same PID still owns it.
  3. Confirm identity: process name and start time match what you saw (guards against PID reuse).
  4. SIGTERM — a polite request to quit (kill <pid>).
  5. Wait briefly and check the process exited.
  6. Verify the port is released.
  7. If the process is still alive, PortPeek shows a Force Kill option. Only if you confirm, it revalidates again and sends SIGKILL.

PortPeek never escalates to SIGKILL on its own, and refuses to signal PID 1 or itself.

Possible outcomes

Message Meaning
Port freed Process exited and the port is released
Already exited The process was gone before the signal
Port already released The process lives on, but no longer holds the port; nothing was killed
Target changed A different process now owns the port; nothing was killed
Permission denied Your user can’t signal that process — see permissions
Did not exit SIGTERM was ignored; Force Kill is offered

What each utility verifies

Utility After SIGTERM, MacPeek confirms
PortPeek The process exited and the port is released
FileLockPeek The process exited and the file is no longer held by that PID. If another process now holds it, MacPeek says so
ProcessPeek The process exited. A zombie that has already ended counts as gone

In every case the PID must still be the same process (name and start time) before any signal is sent, and Force Kill is a separate step you choose. Ending loginwindow or your user launchd from ProcessPeek always asks first, because it ends your session. See also permissions and ProcessPeek.