mjhjmtu

I'm running a script which is meant to process a few utilities in order to recover some data. This script is situated in a directory where the users can place their file that needs to be recovered. Since many users can have access to this directory and run the script, I want to have a condition that checks if the script is already running. If yes, then echo a "try again later" message; otherwise, run as usual.

I did some research on here and figured this to be a working code for my functionality as described above.

#!/bin/bash 
me="$(basename "$0")";
running=$(ps h -C "$me" | grep -wv $$ | wc -l);
[[ $running > 1 ]] && exit;

I would like to implement this functionality and the code above in a Solaris SunOS 5.8. I understand that ps functions differently in Unix and Linux.

The ps command you are using is not related to UNIX.

Using key letters instead of options was used in BSD ps but that did never make it into the standard. BSD even uses the h key letter in a different way as you might expect.

I recommend to use:

ps -p $$

If you like to check whether there are more instances of this script, use:

myname=`basename $0`
pids=`pgrep -d, $myname`
ps -p $pids

In theory, you do not even need to run ps anymore, it would be sufficient to check the output of pgrep for a comma.

If you like to implement a lock file algorithm and have a POSIX compliant shell, you may use:

set -o noclobber
:> /var/tmp/myscript
if [ $? -ne 0 ]; then
 echo already running
 exit 1
fi
... do some stuff
rm /var/tmp/myscript

Whether this works reliably depends on whether the shell implements noclobber the way POSIX likes to see it. Some shells may not implement this atomically, so you need to know whether your shell is OK.