> I am in the process of developing a few scripts that:
> 1) pull images off a CF card on my laptop
> 2) move the images to a server
> 3) rename the images on the server according to the EXIF info
>
>
> I figure that for 2 & 3, the easiest way to make sure they work is to have 
> them run in a cron job once a minute (or five). (Wake up, check to see if 
> there's any work, either do it or quit.)
>
> The problem is that I need to make sure that if the script starts while 
> another copy of the script is running, it quits. I can work out how to create 
> lock files, stick in PIDs to make sure the script is really there, etc. But 
> it seems like someone must have tackled this problem already (IIRC, I ran 
> across a Perl module that back in my misspent youth).
>
> Does anyone know of a gem (or just some canonical code) that handles this 
> easily?
>
> Paul
>
> PS I've also thought about using 'daemonize', but I'd still have to worry 
> about locking.
>

Just a followup: I've taken a closer look at 'daemons', and it actually 
will only allow one instance of the script to run at once. That combined 
with a cron job to make sure the script is still running, and I'm good to 
go on this front.

Paul