Quick Question about Monitoirng Files

I have been tasked with monitoring a few flat files and read the content of the files and return the results to nagios. Based on that I would also have to be able to trigger alerts based off the numerical value example:
<> or = 1000 and trigger based off the number. I have been looking out there for something like this but have run into a dead end. The files also resides on a windows server, but if thats an issue i can ftp over to the nagios server. Any Help would be appreciated.

You are going to read the contents and look for what or do what? check_log will read log files and look for “query whatever characters”