Comments on: One instance at a time with PID file in Bash

By: Craig

Craig — Wed, 11 May 2011 14:09:17 +0000

You should also check if they process_id that is running is actually the same script. The system could release the script and then re-issue that process_id to another program.

By: Sharad Agarwal

Sharad Agarwal — Sat, 11 Sep 2010 16:31:19 +0000

Maybe we can try to modify your run_one_instance.sh script a bit to make it so that the can be any other script?

No copy/paste that way, and makes it more interesting

By: Jonathan

Jonathan — Sat, 28 Aug 2010 02:06:03 +0000

Hi,

Your syntax is a bit wrong, when I ran the command the output of kill got redirected to the file 1.

Here is the syntax that worked for me:

if kill -0 $pid > /dev/null 2>&1; then
echo “Already running”
exit 1
else
rm $pidfile
fi
fi
echo $$ > $pidfile

By: Gerard Seibert

Gerard Seibert — Mon, 30 Nov 2009 12:18:16 +0000

I modified your script slightly. It works on Bash and does not create a ’1′ file. Using the ‘f’ flag with ‘rm’ also prevents useless error messages.

PID_FILE=”/var/run/my_prog.pid”

## Check to see if the program is running
if [[ -e ${PID_FILE} ]]; then
## Capture the ‘pid’ number in ‘pid’ variable
pid=$( ${PID_FILE}

do something

## Remove the pid file if it exists
if [[ -e ${PID_FILE} ]]; then
rm -f ${PID_FILE}
fi

By: Samat Jain

Samat Jain — Mon, 16 Feb 2009 23:56:39 +0000

Related and probably interesting to you: over at the sysadvent log there’s an article on best lockfile practices.