| -d | --directories=ACTION | how to handle directories `read', `recurse', or `skip' |
| -E | --extended-regexp | PATTERN is an extended regular expression |
| -R -r | --recursive | equivalent to --directories=recurse |
| | --include=FILE_PATTERN | search only files that match FILE_PATTERN |
| | --exclude=FILE_PATTERN | skip files and directories matching FILE_PATTERN |
| | --exclude-from=FILE | skip files matching any file pattern from FILE |
| | --exclude-dir=PATTERN | directories that match PATTERN will be skipped. |
| -i | --ignore-case | ignore case distinctions |
| -n | --line-number | print line number with output lines |
| -s | --no-messages | suppress error messages |
| -v | --invert-match | select non-matching lines |