check_file_md5

Modeled after check_file_md5s, this script performs the following functions:

- Permits arbitrary md5sum checking of a filename passed in on a parameter
- Builds a list of files with every md5 check - warns when file isn't in the list and adds the file
- Critical alert when a file is not present
- Critical alert, followed by a refresh of the list of checksums when an md5 checksum doesn't match

Default location of temporary list of md5 checksums is /usr/local/nagios/ - modify this line of the script if you wish to change.

Tested and currently running on an array of CentOS 4.x and 5.x servers, but this should work on any UNIX/Linux server with which & md5sum installed.

Planned for future development (and encouraged from the community):
- Would be nice to store cache of md5sums on nagios instead of local server
- Also would be nice to make use of additional parameters to activate or suppress cache-auto-updates