Package grep

Pattern matching utilities

http://www.gnu.org/software/grep/

The GNU versions of commonly used grep utilities. Grep searches through
textual input for lines which contain a match to a specified pattern and then
prints the matching lines. GNU's grep utilities include grep, egrep and fgrep.

GNU grep is needed by many scripts, so it shall be installed on every system.

General Commands (Section 1)
grep
grep searches the named input FILEs for lines containing a match to the given PATTERN. If no files are specified, or if the file “-” is given, grep searches...