From: Tom Cloyd <tomcloyd@...>
Date: 2009-01-17T02:46:59+09:00
Subject: Re: RubyGem, find path of installed gem through ruby.

Tom Cloyd wrote:
> Aaron Smith wrote:
>
> Hey Tom, Thanks, that information is definitely what I'm looking for. 
> How would I get that info from within a ruby script. Specifically the 
> "GEM PATH" is what I would need. Is there a method to get that?
>
> or rather, the "INSTALLATION DIRECTORY."
>
> ===========================
>
> If you had any idea how paltry my knowledge of Ruby really is you 
> would ask me such questions! But...I got us this far, so...
>
> I think I'd try a system call to "gem env", and put the output in a 
> string, then locate "INSTALLATION DIRECTORY:" with StringScanner, and 
> take everything after that, up to the EOL as the path you're after. 
> Easy, actually.
>
> Only I'm momentarily stumped as to how to make the system call AND 
> capture the output. Thomas (Pickaxe 2) says it can be done using 
> backtics. I tried it in irb and got nothing. Still trying to figure it 
> out. It'd be a good trick to know.
>
> t.
>
Bummer. In order to preserve my reputation, I managed to get irb a bit 
hung up, so of course it didn't perform `gem env` as I expected. 
Ungummed, as it were, it works fine. E.g.:

irb(main):001:0> a=`gem env`
=> "RubyGems Environment:\n  - RUBYGEMS VERSION: 1.3.1\n  - RUBY 
VERSION: 1.8.7 (2008-08-11 patchlevel 72) [i486-linux]\n  - INSTALLATION 
DIRECTORY: /usr/lib/ruby/gems/1.8\n  - RUBY EXECUTABLE: 
/usr/bin/ruby1.8\n  - EXECUTABLE DIRECTORY: /usr/bin\n  - RUBYGEMS 
PLATFORMS:\n    - ruby\n   - x86-linux\n  - GEM PATHS:\n     - 
/usr/lib/ruby/gems/1.8\n     - /home/tomc/.gem/ruby/1.8\n  - GEM 
CONFIGURATION:\n     - :update_sources=> true\n     - :verbose => 
true\n     - :benchmark => false\n     - :backtrace => false\n     - 
:bulk_threshold => 1000\n  - REMOTE SOURCES:\n     - 
http://gems.rubyforge.org/\n"
irb(main):002:0>

I leave it to you to get the code to have StringScanner find and return 
the path. Somehow I keep thinking regular expressions might be helpful 
here, but I dare not there. I think I hear the ice cracking already.

t.

-- 

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Tom Cloyd, MS MA, LMHC - Private practice Psychotherapist
Bellingham, Washington, U.S.A: (360) 920-1226
<< tc@tomcloyd.com >> (email)
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<< sleightmind.wordpress.com >> (mental health weblog)
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