About

Use this tag for questions about options for shell commands: passing them and parsing them.

There are three common variants of option syntax; different commands use different syntax.

• POSIX: This is the traditional Unix style. Options consists of a - (dash a.k.a. minus) followed by a single letter. If - is followed by multiple letters, each letter is an option (this is called bundling). Example: ls -la is equivalent to ls -l -a.
  An option can take an argument, which is either in the next word or glued to the option. Example: sort -st: is equivalent to sort -s -t :.
• GNU: in addition to the POSIX syntax, options can start with -- and consist of multiple letters. Arguments are either given after a = or in the next word. Example: sort --stable --field-separator=: is equivalent to sort --stable --field-separator :.
• Multi-letter: an option consists of a - followed by more characters (usually letters and dashes). If there is an argument, it is in the next word. Example: xterm -name foo -e foo

Further reading

• How do I delete a file whose name begins with "-" (hyphen a.k.a. dash or minus)?
• Is `-` used only with cd?
• Single dashes `-` for single-character options, but double dashes `--` for words?
• What is the difference between "du -sh *" and "du -sh ./*"?