A basic library for creating lockfiles for processes

This library works with Ruby 1.8 and 1.9 and is licensed under the MIT License.


The pidfile gem is hosted on ( This requires that you have in your gem sources.

Install the pidfile gem:

sudo gem install pidfile

Gettings Started

The pidfile gem is easy to use and only requires the instantiation of the pidfile, like so:

pf =

Of course there is other functionality, but if you are just wanting to keep a process from running more than once, this is all you need.


PidFile creates file to store the process ID (PID). By default, process ID (PID) files are created in /tmp upon instantiation and are given the same name as the calling script with a .pid extension. Process ID files are removed when the creating program exits.

Each argument, :pidfile and :piddir, can be changed upon instantiation of the class.

Example: => '/var/lock', :pidfile => "")


Why isn't this a singleton?

My main concern is how it would behave when a process is forked multiple times. Each new process would get its own PID, but I wasn't sure how using a singleton would affect this; if the interrelationship of the processes would keep the object from correctly identifying the correct pidfile.

Anyway, I like the flexibility that not using a singleton offers, and I guess I'd rather ask you not to do something bad rather than restraining you.

Copyright© 2010 Samuel Mullen (samullen). See LICENSE for details