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
RHEL/CentOS: yum install jwhois

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 fork, hosted at https://github.com/Elyrith/check_domain
Currently supports .com, .ca, .tv, .ee, .ru, .net, .nu, .se, .org
Support for .ca and .se by Ryan Loudfoot (elyrith@gmail.com)
Support for .net, .nu and .org 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:
2014-09-06 - Version 1.0!
-Using whereis command to find the whois binary
  ("whois on first, whereis on second..." -geekiest Abbot and Costello?)
-Add help text for -P switch
-Add RHEL/CentOS command for installing whois command (jwhois package)

2014-06-26 - Version 0.99
-Add support for .org domains thanks to Jack-Benny Persson (jack-benny@cyberinfo.se)

2014-02-21 - Version 0.98
-Fix support for .ca domains, not sure why it broke but it's fixed now.
-Fix spacing in comment for utils.sh
-Add note that the source repo has been updated
-Mention .se support in "Currently supports" line in readme

2013-12-16 - Version 0.97
-Fix support for .nu domains thanks to Jack-Benny Persson (jack-benny@cyberinfo.se)

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