Search text files for matching strings

I need some help.

Here's what I would like to do. I'd like to import a test file with a list of search terms. Then I'd like to have the program search another text file to see if the terms exist.

The input file will be a list of server names and/or IP addresses, so they will be a single item per line.

The text file to be searched is a router configuration, so each line will vary in length.

Any thoughts on the best way to do this?

Thanks.

grep, and/or Perl. :)

If you want to code it yourself, in C++, you could create a std::set of the search terms, and then for each term in the "other file", just check to see if it exists in the std::set. That would probably be more efficient but less esoteric and less fun than using grep.