Search one or more
files for lines that match a
regexp. Regular expressions are described
in Section 6.
Exit status is 0 if any lines match, 1 if not, and 2 for errors.
See also egrep and fgrep.
Precede each line with its block number.
Print only a count of matched lines.
Print matched lines but not filenames (inverse of -l).
Ignore uppercase and lowercase distinctions.
List filenames but not matched lines.
Print lines and their line numbers.
Suppress error messages for nonexistent or unreadable files.
Silent mode: print only error messages, and return the exit status.
Print all lines that
regexp to matching a whole word
(like using < and >> in vi).
List the number of users who use the C shell:
grep -c /bin/csh /etc/passwd
List header files that have at least one #include directive:
grep -l '^#include' /usr/include/*
List files that don't contain
files| grep :0