kill & killall

Sends a signal to a process — usually asking it to terminate, gracefully or not.

Terminate a process

SHELL

1kill <pid> # SIGTERM — ask it to shut down cleanly

2kill -9 <pid> # SIGKILL — force, no cleanup

3killall <process-name> # by name instead of PID

-9 / SIGKILL gives the process no chance to flush buffers or close files cleanly. Try a plain kill first and only escalate if it doesn't respond.