java - Command line options style - POSIX or what? - Programmers Stack Exchange

java - Command line options style - POSIX or what? - Programmers Stack Exchange

EDIT: It's been pointed out that this style is a GNU-ism, and that non-GNU based Unixes tend to use a single-dash syntax (in particular, OS X and BSD variants).

Despite it's GNU-ism status, many newly written Unix-style programs use this style:

• --long-option for long option names,
• -s for short (one-character) options,
• -abc for multiple short options without arguments (one character per option).
• Options with arguments:
  • --long arg or --long=arg for long options,
  • -s arg, -sarg or (optionally) -s=arg for short options. This can be combined with other short options, as long as only the last one has an argument.
• The same "semantic" option can have several aliases, most commonly a short (quicker to type) one and a long (easier to remember) one.

Anybody that has used a Linux shell for any amount of time should be familiar with this style¹, so it has the principle of least surprise on its side. Allowing grouping of multiple short options without being ambiguous with long options is also nice.

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