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Ways to 'kill' With Linux
To kill or not to kill
January 8, 2009
... other than what its name implies.
kill is most often used without an argument or with -9,
to kill a process off. But it can also be used to send various other signals
to a process. Some are variations on process termination, but you can
also get information about or out of processes.
- kill -0 pid: This doesn't actually kill the process, just
returns 0 (success) if the process exists and 1 (failure) if not. The
command itself will not give you any output — you have to look at the
exit code, using echo $? to get the information. So as
kill -0 1685; echo $?
will output 0 if process 1685 exists, and 1 if it doesn't. This can also
be useful in shell scripts if you have a process number recorded and wish
to check if it's still running.
- kill -9 pid: You probably already know that you can terminate the
process WITH EXTREME PREJUDICE. kill -KILL does the same thing
and has the advantage of looking more vicious. The downside is that it is an extra couple of characters to type.
- kill -HUP pid: Restarts the process.
- kill -INT pid: Another way of killing the process, this time
by interrupting it. It is a useful halfway house between kill and
- kill -ABRT pid: Stops your program and gets it to dump core
if possible/appropriate. (kill -6 is a synonym.)
This can be useful if a process is misbehaving, as it means that you may get debug information.