Meaning of killall -0
I see from many place the follow command is used to check if a process exists, e.g.
killall -0 nginx
But from the documentation I can't see anything related to this argument, can anyone explain?
Solution 1:
man kill
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.
killall kill processes by name instead of PID on Linux & BSD-based systems.
In other Operating Systems (Solaris), the killall command is used to terminate all running processes.