Safe Way to Tell if Process is Running
martin at dc.cis.okstate.edu
Tue Dec 4 20:01:44 UTC 2012
About 20 years ago, I saw some code in which you
verified whether or not a process was running by giving it a
kill -0 command. If the process was running, nothing happened to
it but your kill -0 command exited with a 0 status. If there was
no process with that PID, the kill command exited non-zero.
I use this in a system(command); in a C program I wrote
some years ago and I think this is now causing a segmentation
fault when the process number being signalled doesn't exist. Is
there a better way to determine if process number 12345 is
running without bothering it?
None of the documentation on kill (1) shows a signal 0
nor does kill -l.
Something tells me this is a bad idea these days, but I
still need an easy way to see if XYZ process is still alive.
Martin McCormick WB5AGZ Stillwater, OK
OSU Information Technology Department Telecommunications Services Group
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