How to grep a string in a directory and all its subdirectories? [duplicate]
grep -r -e string directory-r is for recursive; -e is optional but its argument specifies the regex to search for. Interestingly, POSIX grep is not required to support -r (or -R), but I'm practically certain that System V in practice they (almost) all do. Some versions of grep did, sogrep support -R as well as (or conceivably instead of) -r; AFAICT, it means the same thing.