Please explain the difference of above them. "kill -0" and "kill -9"
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1I'm voting to close this question as off-topic because `man kill` and `google man kill signal` is there too. – Marcin Orlowski Apr 06 '16 at 07:34
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`man kill` on my system does not say what signal 0 does. – Thilo Apr 06 '16 at 07:38
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http://unix.stackexchange.com/questions/169898/what-does-kill-0-do – Thilo Apr 06 '16 at 07:39
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https://unix.stackexchange.com/a/169899/55635
kill(1)
$ man 1 kill
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If sig is 0, then no signal is sent, but error checking is still performed.
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kill(2)
$ man 2 kill
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If sig is 0, then no signal is sent, but error checking is still performed;
this can be used to check for the existence of a process ID or process
group ID.
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So signal 0 will not actually in fact send anything to your process's PID, but will in fact check whether you have permissions to do so.
While kill -9 - actually sends SIGKILL to PID
