On Fri, Apr 15, 2022 at 09:47:11PM -0400, The Wanderer wrote: > On 2022-04-15 at 20:47, Greg Wooledge wrote: > > > On Sat, Apr 16, 2022 at 08:20:40AM +0800, wilson wrote: > > >> ps -efw |grep $PS |grep -v grep > > > You're also going to exit your script with the exit status from that > > last grep command. That's probably not what you want. If it's not, > > then an explicit "exit 0" at the end might be a good idea. > > > > Or, as another choice, you might want to exit with the exit status > > of the *first* grep. In that case, switching them around would be > > better: > > > > ps -efw | grep -v grep | grep "$PS" > > This would probably result in undesired behavior. I recognize this > pattern [...] If all you want to do is to find out whether a process with PID "$PS" is running, why not ps --pid "$PS" > /dev/null 2>&1 && echo "yo" or even perhaps kill -0 "$PS" 2>/dev/null && echo "yo" But yes, for the general pattern you are right. Cheers -- t
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