Alex Zbyslaw wrote:
Eric Schuele wrote:
Hello,
I am sure this is quite trivial, but...
I have need to determine if an app (firefox, or anything really) is
already running before I perform some action. So I grep the ps
output. However sometimes (many times) that which I'm searching for
is present in the output because I am presently grep'ing for it. But
it is not always there. It seems to be a bit inconsistent. (See below).
I was wondering if someone could explain why it is sometimes there and
not other times. And how I should correctly go about detecting if the
process is running before I perform my action.
ps | egrep firefox | egrep -v egrep
Thanks guys. Yes... both solutions do fix the problem.
Hmm... guess I should've looked before I lept. I assumed the processes
were run in order by the shell... however it appears all are started
simultaneously as a group.
I can't explain exactly why. It's clearly a timing thing. I guess if
the ps runs quickly enough then perhaps the grep hasn't actually been
started by the shell.
Or if ps iterates over something, then maybe the
grep appears in a part of the list that has already been looked at by ps.
--Alex
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--
Regards,
Eric
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