kill

kill is used to send signal to a process or to kill a process. We typically use kill PID, where you know the PID of the process. By default kill generates SIGTERM, to safely end a process.

$ kill 7243

Useful Options / Examples

kill [-s] %pid

$ ps -ef | grep vim
username    7243  7222  9 22:43 pts/2    00:00:00 vim

$ kill -9 7243
Break it down
  • ps -ef will print out all the processes running on the user’s machine. Piping with | grep vim will only output processes with the name given, in this case only vim processes are printed. kill -9 7243 is using SIGTERM -9 to send the end process (kill) signal to process 7243, which will kill that vim process.

killall

$ killall -9 firefox
Break it down
  • killall allows a user to kill processes (using signal -9) by name, here the firefox process is being killed

pkill

$ pgrep -l sample
12406 sample-server.p
12425 sample-server.p
12430 sample-garbagec

$ pkill -9 sample
Break it down
  • pgrep displays the process ID and process name of the matching processes. pkill can send signal to any process by specifying the full name or partial name. So there is no need for you to find out the PID of the process to send the signal.