Making sure script only runs once instance at a time.

[Lawrence D'Oliveiro]

In message <mailman.949.1159543590.10491.python-list at python.org>, Tim
Williams wrote:

> On 29/09/06, Matthew Warren <Matthew.Warren at digica.com> wrote:
>> I have found that in real usage of other programs within the company that
>> use lockfiles, it sometimes causes a bit of troubleshooting time when it
>> stops working due to a stale lockfile.. This especially happens when the
>> program is killed, the lockfile remains and causes minor annoyance (to
>> somebody who knows that is, more annoyance to somebody who doesn't).
> 
> Then they were checking for the wrong thing :)      Chcking for a lock
> file's existance is prone to the above problem.

My script deals with this
<http://groups.google.co.nz/groups?selm=ldo-727939.19244215042006@lust.ihug.co.nz>.