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Old 06-04-2004, 05:57 PM   #1
Utah
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What are those double-dash (--) options in man?


When I look at man pages, most commands seem to have some options listed with a double dash "--" in front of them.

For instance, man rpm lists options:

--quiet Print as little as possible
-v Verbose

Why does the Verbose option use one dash but the Quiet option use two?


Thanks in advance,

Utah
 
Old 06-04-2004, 06:10 PM   #2
XavierP
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As far as I can tell, switches that use a letter (like -a) only need a dash, but those that use a word, don't. But I have no idea why - probably something from Unix.
 
Old 06-04-2004, 06:19 PM   #3
darthtux
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They are gnu additions to the options to make some of them clearer. The man pages in Slackware make a distinction between industry standard POSIX options and the gnu ones each being under their own section.
 
Old 06-04-2004, 06:23 PM   #4
XavierP
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You live and learn
 
Old 06-04-2004, 10:53 PM   #5
Tino27
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I think additionally that single character options can be strung together on a single '-'.

For example...

tar -xvzf source.tar.gz

instead of (but is functionally the same as)

tar -x -v -z -f source.tar.gz

'--' options are actually single options that are more than one letter.

So...

tar --xvzf source.tar.gz

would actually force the tar program to look for a single option named 'xvzf'.

You can also mix and match, such as

ls -al --co

which will list all (-a) of the contents of the current directory in long (-l) format and apply color (--co) to the display based on the type of file listed on the screen.

Hope that helped.
 
  


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