[clue-tech] cron jobs off to the races

[Bruce Ediger]

On Sat, 2 Jan 2010, chris fedde wrote:

> # exclusion
> if test -f $pid
> then
>    pid=`cat $pidfile`
>    if kill -0 $pid
>    then
>        echo $0 running as $pid > STDERR
>        exit 1
>    fi
> fi
> echo $$ > $pidfile

Let me emphasize that you want to do the "kill -0 $PID" technique, even if
it means mucking around with a PID in a file in /var/run (or whatever).

DO NO EVEN CONSIDER doing a "ps -ef | grep SomeProgramName" - it is
unreliable in some marginal situations, and it WILL cause you trouble.

Only amateurs do the "ps -ef | grep ProgName" thing.