mirror of
https://github.com/flokoe/bash-hackers-wiki.git
synced 2024-11-01 14:53:06 +01:00
21 lines
1.1 KiB
Plaintext
21 lines
1.1 KiB
Plaintext
|
====== 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]]
|