grep - search a file for lines containing a given pattern

     grep [-elnsv] pattern [file] ...


     -e   -e pattern is the same as pattern

     -c   Print a count of lines matched

     -i   Ignore case

     -l   Print file names, no lines

     -n   Print line numbers

     -s   Status only, no printed output

     -v   Select lines that do not match


     grep mouse file     # Find lines in file containing mouse

     grep [0-9] file     # Print lines containing a digit


     Grep searches one or more files (by default, stdin) and selects  out  all
     the  lines  that match the pattern.  All the regular expressions accepted
     by ed and mined are allowed.  In addition, + can be used instead of *  to
     mean 1 or more occurrences, ? can be used to mean 0 or 1 occurrences, and
     | can be used between two regular expressions to mean either one of them.
     Parentheses can be used for grouping.  If a match is found, exit status 0
     is returned.  If no match is found, exit status 1  is  returned.   If  an
     error is detected, exit status 2 is returned.

     cgrep(1), fgrep(1), sed(1), awk(9).