print lines matching a pattern

-I     Process  a  binary  file  as  if  it  did  not  contain  matching  data; this is equivalent to the
       --binary-files=without-match option.

    -R, -r, --recursive
           Read all files under each directory, recursively; this is equivalent to the -d recurse option.

Other Options
    --line-buffered
           Use line buffering on output.  This can cause a performance penalty.

-l, --files-with-matches
       Suppress normal output; instead print the name of each input file from which output would normally
       have been printed.  The scanning will stop on the first match.  (-l is specified by POSIX.)