Ensure only single application instance.

[Uberman]

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.

You could create a named pipe in /tmp with a unique (static) name and
permissions that disallow any kind of read/write access.  Then simply have
your script check for its existence when it starts.  If it exists, then
another instance of your script is running, and just terminate.  Make sure
your original instance removes the pipe when it exits.