Hi Dan,
I notice that piping it through wc and doing the "-eq 0" is not neccessary, as grep
will return
"false" if it can't match the pattern. "-eq 0" is much more friendly, of course :-)
I like your psg alias i think i'll use it! I"ve noticed that grep will often not catch
it's own
process the first time you filter a ps list but that it will the second, third, etc
time.
Cheers,
j
--- Dan Woods <[EMAIL PROTECTED]> wrote:
>
> Karl Cunningham wrote:
> >
> > I'm writing a shell script that will have problems if another instance of
> > itself is running, and I'd like to be able to trap that the user has
> > started multiple instances. I've tried
> >
> > cnt=`ps ax | grep -c xyz`
> >
> > where xyz is the name of the script. It returns 3 when there is only one
> > instance running. I think I understand why it's 3 (one for the script
> > itself, one for it running ps and one for it running grep?). Will this
> > always work? Is there a better way?
>
> This works from command line...
>
> # if [ `ps -efw | grep -v grep | grep rerf |wc -l` -eq 0 ] ; then
> echo 'yes' ; else echo 'no' ; fi
>
> In a shell script, make it more readable...
> if [ `ps -efw | grep -v grep | grep rerf |wc -l` -eq 0 ]
> then
> echo 'yes'
> # more statements here, etc.
> else
> echo 'no'
> fi
>
> -----
> Also, analias command that I use *often* is
> # alias psg
> alias psg='ps -efw | grep -v grep | grep'
>
> This avoids seeing the 'grep' that is forked off by your request.
>
> Thanks...Dan
>
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