There comes always a time, where you’ll have to find files, containing a certain text. Furtunately this is an easy task on UNIX based systems.

You can search “foobar” in all files with:

find . -type f -exec grep -l "foobar" {} \;

With that, you’ll search first for all files in the current and all subdirectories and execute an in-file search with grep.

Further information you’ll find on the manpages of those two tools