UNIX for Dummies Questions & Answers

Try this

Code:

#!/usr/bin/ksh

#
# Check script in use
#

LockFile=/tmp/$(basename $0).lck
echo $$ >> $LockFile
while read Pid
do
   [ "$Pid" -eq $$ ] && break
   [ -z "$(ps -p $Pid -opid=)" ] && continue
   echo "Script in use (by pid $Pid), exiting..."
   exit
done < $LockFile
trap "rm $LockFile" EXIT

#
# Script code
#

. . . . . . .

This is similar to the method that I use and so far, nothing has ever conflicted since I ironed out one wrinkle. I haven't tested this particular implementation and maybe it doesn't have the same hole that I found in my first attempt but, you may want to included ps -fp $pid | grep yourscript to eliminate the possibility of other processes giving you false positives; some systems can reuse PIDs fairly quickly. My Solaris implementation was plagued by false positives for a month (between release cycles) until I added the grep.

The temp file solution doesn't work, since if the script is interrupted or crashes out before the final line, the temp file is never deleted and you'll always think the script is running.

use 'trap' to catch an interrupt.

look into 'man fuser'

Yes, sorry I meant that the temp file version posted by DogDay doesn't work:

Of course, the version posted by aigles with PID check and "trap" works perfectly every time.