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32 lines
1.1 KiB
Markdown
32 lines
1.1 KiB
Markdown
# End of Options
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The options of UNIX(r) utilities usually are introduced with a dash
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(`-`) character.
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This is problematic when a non-option argument has to be specified that
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begins with a dash. A common example for this are filenames.
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Many utilities use the convention to specify two consecutive dashes
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(`--`) to signal \"end of options at this point\". Beyond this tag, no
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options are processed anymore, even if an argument begins with a dash.
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Example: You want to list (`ls`) the file with the name `-hello`. With
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common option processing, this could end up in the ls-options `-h`,
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`-e`, `-l` and `-o` and probably in an error message about invalid
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options. You use this to avoid the wrong option processing:
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ls -- -hello
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POSIX(r) specifies that every utility should follow this rule (see ch.
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[12.2 Utility Syntax
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Guidelines](https://pubs.opengroup.org/onlinepubs/9699919799.2013edition/basedefs/V1_chap12.html)),
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except
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- `echo` (historical reasons)
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- `test` (obvious parsing reasons)
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## See also
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- Scripting article, internal:
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[getopts_tutorial](/howto/getopts_tutorial)
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