process control

From: Leiji Liu (leijiliu_at_nexrain.com)
Date: 07/30/03 

Date: Wed, 30 Jul 2003 21:57:47 GMT

Hi,

I have a piece of script which runs periodically from cron table. In order
to prevent the second copy of the same code from running simultaneously, I
have to "ps" the current status of memory and if there is one copy running,
the second will not start. A guru gave me following piece (on Solaris
system):

The script's name is "allrun.sh".

#!/bin/ksh
check=`ps -ef |grep "/bin/ksh /home/mycode/allrun.sh" | wc -l`
if [ $check = 2 ] ; then
    process my programs
fi

Here is the question. Why should the $check be 2? Or should it be better
$check < 2? When I manually start "allrun.sh" (not from cron table) from
command line, the $check is 0. Can anybody give me some explanation?

Thanks a lot!

ll

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