Help wrt to Unix script using egrep

Question

In one of our script, we are checking whether already an instance of process is running in the system using the commands ps and egrep.
An intermediate process is created with the same name as original process before invoking the egrep, which is resulting the result of grep to be incorrect.
The following code is in the script /opt/check.sh is resulting in the problem.
RESULT=`/usr/ucb/ps -auxww | egrep "/opt/check.sh ${PARAM}" | grep -v "log" | grep -v "grep" `
The above code is
solaris9{root} #: ps -ef | egrep "/opt/check.sh"
nmsadm 11500 11498 0 10:45:16 pts/6 0:00 egrep /opt/check.sh -s
nmsadm 11498 11431 0 10:45:16 pts/6 0:00 /bin/sh /opt/check.sh -s
nmsadm 11431 28568 0 10:45:13 pts/6 0:00 /bin/sh /opt/check.sh -s
solaris9{root} #: ptree 11498
We are using solaris9.
If anyone has any idea pleas let me know.
Thanks in advance

Answer 1

OK, I agree, current script will be also displayed, but my solution is still better ;)
pgrep -x program_name | grep -v $$
One line, and so easy. But if you really want to have only one instance of some script at the time I propose you another solution:
#!/bin/bash
# location of lock file, /var/run is quite good place because it's empty
# after every reset (virtual filesystem placed in memory). Many of other
# Solaris application puts his lock files here
LOCK=/var/run/somescript.lock
# check if there is lock file
if [ -e $LOCK ]
then
# some error message
echo "Another instance is running allready. Exiting." >&2
# if you want to now everything about running instance
ps -fp `cat $LOCK`
# exiting now
exit 1
fi
# to be sure that lock file will be deleted at the end of execution
trap 'rm -f $LOCK' EXIT
# here lock file with process PID is created
echo $$ > $LOCK
< here is the rest of your script unchanged>
This solution is better if you only want to be sure, that there is only one instance of process running at one time. Previous one, with pgrep, if you want to check if another script is running. I missunderstood your question at the beginning.
Hope this helps.
Regards