This is a Nagios plugin to check the expiration date of a domain name.
It uses the "whois" command, which usually comes as a "whois" package.
Debian/Ubuntu: apt-get install whois

Original version had this copyright notice in it:
Copyright (c) 2005 Tomàs Núñez Lirola <tnunez@criptos.com>,
     2009-2012 Elan Ruusamäe <glen@delfi.ee>, under GPL License

Ryan found it hosted at:
http://git.pld-linux.org/gitweb.cgi/?p=packages/nagios-plugin-check_domain.git

This is a modified version, hosted at https://github.com/Elyrith/check_domain
Currently supports .com, .ca, .tv, .ee, .ru, .net
Support for .ca and .se by Ryan Loudfoot (elyrith@gmail.com)
Support for .net by Jack-Benny Persson (jack-benny@cyberinfo.se)
Support for Performance Data by Ryan Loudfoot

If you would like to add a TLD, send me the code or a pull request. If you want me to add one, let me know and I'll see what I can do.

Change log:
2013-11-28 - Version 0.96
-Add support for .net domains thanks to Jack-Benny Persson (jack-benny@cyberinfo.se)

2013-09-06 - Version 0.92
-Modified the .com result to work for more domains since not all registrars have everything the same way
-Change readme to be lower-case for the file name
-Created changelog