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Standard Command-Line Options

F.1. Standard Command-Line Options

Over time, there has evolved a loose standard for the meanings of command line option flags. The GNU utilities conform more closely to this "standard" than older UNIX utilities.

Traditionally, UNIX command-line options consist of a dash, followed by one or more lowercase letters. The GNU utilities added a double-dash, followed by a complete word or compound word.

The two most widely-accepted options are:

  • -h

    --help

    Help: Give usage message and exit.

  • -v

    --version

    Version: Show program version and exit.

Other common options are:

  • -a

    --all

    All: show all information or operate on all arguments.

  • -l

    --list

    List: list files or arguments without taking other action.

  • -o

    Output filename

  • -q

    --quiet

    Quiet: suppress stdout.

  • -r

    -R

    --recursive

    Recursive: Operate recursively (down directory tree).

  • -v

    --verbose

    Verbose: output additional information to stdout or stderr.

  • -z

    --compress

    Compress: apply compression (usually gzip).

However:

  • In tar and gawk:

    -f

    --file

    File: filename follows.

  • In cp, mv, rm:

    -f

    --force

    Force: force overwrite of target file(s).

Caution

Many UNIX and Linux utilities deviate from this "standard," so it is dangerous to assume that a given option will behave in a standard way. Always check the man page for the command in question when in doubt.

A complete table of recommended options for the GNU utilities is available at http://www.gnu.org/prep/standards_19.html.