End of Options [Bash Hackers Wiki]

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====== End of Options ======

The options of UNIX(r) utilities usually are introduced with a dash (''-'') character.

This is problematic when a non-option argument has to be specified that begins with a dash. A common example for this are filenames.

Many utilities use the convention to specify two consecutive dashes (''<nowiki>--</nowiki>'') to signal "end of options at this point". Beyond this tag, no options are processed anymore, even if an argument begins with a dash.

Example: You want to list (''ls'') the file with the name ''-hello''. With common option processing, this could end up in the ls-options ''-h'', ''-e'', ''-l'' and ''-o'' and probably in an error message about invalid options. You use this to avoid the wrong option processing:
<code>
ls -- -hello
</code>

POSIX(r) specifies that every utility should follow this rule (see ch. [[https://pubs.opengroup.org/onlinepubs/9699919799.2013edition/basedefs/V1_chap12.html|12.2 Utility Syntax Guidelines]]), except
  * ''echo'' (historical reasons)
  * ''test'' (obvious parsing reasons)

===== See also =====

  * Scripting article, internal: [[howto:getopts_tutorial]]

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