Ensure only single application instance.

[Timothy Grant]

On Fri, Aug 29, 2008 at 6:51 AM, Heston James <heston_james at live.co.uk> wrote:
> Good afternoon all.
>
> I have an application/script which is launched by crontab on a regular
> basis. I need an effective and accurate way to ensure that only one instance
> of the script is running at any one time.
>
> After a short look around the internet I found a couple of examples, such as
> this one (http://code.activestate.com/recipes/474070/), however they both
> seem to be focused on a windows based environment.
>
> Can anyone offer their advice on how best to do this on a linux based
> system?
>
> I have been contemplating the idea of creating a pidfile which is destroyed
> at the end of the script, will this suffice? is it fool proof? My only
> concern with this is that if the script crashes or is stopped halfway
> through processing for whatever reason, I'll be left with a dead pidfile on
> the system and no successive runs will work.
>
> I'm really interested to get your ideas guys, Thanks.
>
> Heston
>
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Why not look at the process list, and if you find two entries kill the
one that is just starting?


-- 
Stand Fast,
tjg. [Timothy Grant]