Darrin Chandler  wrote:

quoted text
> If you really want to find the parent you can...

>

> $ ps ax -O pgid | grep ntpd

> 4887  4887 ??  Is      0:00.01 ntpd: [priv] (ntpd)

> 7164  4887 ??  I       0:00.06 ntpd: ntp engine (ntpd)

>

> The header that gets stripped by grep:

> PID  PGID TT  STAT       TIME COMMAND

>

> So you can see that for one process PID==PGID. Bingo.

Yes, but there might be a race condition while checking.
What I would like to do is to check if a shell script is already active. And

I don't want to use a lock file:
if [ $(pgrep -of "/bin/sh $0") -ne $MYPID ]; then

        echo "I'm already active:" 1>&2

        echo $(pgrep -olf "/bin/sh $0") 1>&2

        exit 1

fi
If pgrep (with -o support) finds a process that is *older* than MYPID the

script is already active.
afaik that construction is faster than grepping ps, piping and comparing two

values but if there is a better solution I'm pleased to hear about. :)
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