Search under currently directory and sub directories for a string

Question

How can I search all files under a specific directory that contian a specific string sequence like "superuser"

i.e. search for all files in the current directory and sub-directories (recursively) if they contain the world "superuser"

Answer 1

grep's -R option does this:

grep -R "superuser" .

EDIT: to search only .mp3 files and return their names (not the matched content, since they aren't text files anyway), use find to get a list of .mp3's and then use xargs to pass them to grep -l:

find . -name "*.mp3" -print0 | xargs -0 grep -l "superuser"

If your version of find supports -exec ... + (and at least recent OS X's do), you can have find run grep directly:

find . -name "*.mp3" -exec grep -l "superuser" {} +