kill

End a process by its ID

What it does

kill sends a process a signal. The default is TERM, a polite request to exit: the program gets to save its data and close its files. Take the PID from ps or top.

If a process hangs and ignores TERM, kill -9 helps: the KILL signal cannot be caught, and the system stops the process at once. You cannot end other users' processes without sudo.

Careful. After kill -9 the program has no chance to save anything: unsaved data is lost, and temporary files and locks may stay behind. Try a plain kill first.

Syntax

kill <PID>
kill -9 <PID>

Examples

• Ask process 4821 to exit

  kill 4821

  same as: kill -15 4821, kill -TERM 4821, kill -SIGTERM 4821

  • kill — send a signal; TERM ("please exit") by default
  • 4821 — the process ID

• Force the hung process 4821 to stop

  kill -9 4821

  same as: kill -KILL 4821, kill -SIGKILL 4821, kill -s KILL 4821

  • kill — send a signal
  • -9 — KILL: stop at once, with no chance to clean up
  • 4821 — the PID

Related commands

• ps — List processes
• pkill — End processes by name
• systemctl — Manage services: start, stop, start at boot

Practise · All commands