I've seen many command line tools that take a "--" argument. For example:
gem install mysql -- —–with-mysql-config=/usr/local/mysql/bin/mysql_config
What does it stand for? Does it have a special meaning?
asked Oct 20, 2012 at 13:54
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Duplicate of unix.stackexchange.com/questions/11376/… , not superuser.com/questions/372203/…– dset0xOct 20, 2012 at 14:15
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This is not a duplicate, I'm asking a different question here. I'm wondering about the doubledash with no argument name following.– Olivier LalondeOct 20, 2012 at 15:34
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Which is what I said, to the best of my comprehension.– dset0xOct 20, 2012 at 19:28
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Right, my bad. I was referring to the duplicate link created by @Sathya.– Olivier LalondeOct 20, 2012 at 20:22
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I've reopened it, @zmode. My apologies.– Sathyajith Bhat ♦Oct 21, 2012 at 4:52
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2 Answers
It means the tool should stop treating the dash as an option character. For example, suppose you want to search for a dash character in a file:
grep -- - file
In your example the -- is necessary because the gem tool is calling another tool, which also uses dash-prefixed options.
answered Oct 21, 2012 at 5:08
This is common practice when one program, that takes long options, needs to call another program that also takes long options. It signals the first program to stop parsing options, and pass the rest on, unchanged, to the subprocess that it invokes.
