finding previous instance?

[133tcamel]

Hi,
how do I find the previous instance of my perl script?
The script is setup as a cron job and I don't want more than one copy of the script running at the same time..

the method i'm using now is that the script checks for a file.. if it exists then it exits otherwise it touches file when the script starts and removes it when done.. this works but there are many problem with this method :/

Is there any other way of doing it? using the pid ($$)? Not sure but can it be done by capturing the ps output?

any help will be appreciated.

---
cheers!
san.

 

[MikeLacey]

San,

I think your ps approach is the right way to go. You will need to work your way through the process list looking for processes with the same name as yourself -- you will, remember, always find at least one process that matches.

open(PS, 'ps -ef|');
while(<PS>){
$count++ if /$process_name/;
}

print $count; # holds count of matching processes Mike
________________________________________________________________

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