XXX G.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 the GNU standards page .