End of Options
The options of UNIX® utilities usually are introduced with a dash (
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 (
--) to signal "end of options at this point". Beyond this tag, no options are 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
-o and probably in an error message about invalid options. You use this to avoid the wrong option processing:
ls -- -hello
POSIX® specifies that every utility should follow this rule ("utility syntax guidelines"), except
test(obvious parsing reasons)
- Scripting article, internal: Small getopts tutorial