The kill command is most often used to terminate a process. kill can send any signal, but by default it sends a TERM. kill can be used by normal users on their own processes or by root on any process. The syntax is:
kill [-signal] pid
Additional note:
• signal – number or symbolic name of the signal to be sent
• pid – the process identification number of the target process
A kill without a signal number does not guarantee that the process will die, because the TERM signal can be caught, blocked, or ignored. The command kill -9 pid guarantees that the process will die because signal 9, KILL, cannot be caught. Use kill -9 only if a polite request fails.
kill -9 12556
