Unix Command to List files containing string but *NOT* containing another string

Question

How do I recursively view a list of files that has one string and specifically doesn\'t have another string? Also, I mean to evaluate the text of the files, not the filenames.

Answer 1

These answers seem off as the match BOTH strings. The following command should work better:

grep -l  * | xargs grep -c  | grep '\:0'