On Jan 5, 2009, at 9:27 PM, Zhao Yi wrote:

> Tim Hunter wrote:
>> Zhao Yi wrote:
>>> I installed a ruby application by gem. Where can I find its source  
>>> code?
>>
>> gem unpack
>>
>> unpacks a gem to the current directory.
>>
>> gem env
>>
>> shows where gems are installed.
>
> OK, it works. thanks.
> -- 


There's also gem list -d gemname

$ gem list -d rails

*** LOCAL GEMS ***

rails (2.1.2, 2.1.0, 2.0.2, 1.2.6, 1.2.5, 1.2.3)
     Author: David Heinemeier Hansson
     Rubyforge: http://rubyforge.org/projects/rails
     Homepage: http://www.rubyonrails.org
     Installed at (2.1.2): /Library/Ruby/Gems/1.8
                  (2.1.0): /Library/Ruby/Gems/1.8
                  (2.0.2): /Library/Ruby/Gems/1.8
                  (1.2.6): /System/Library/Frameworks/Ruby.framework/ 
Versions/1.8/usr/lib/ruby/gems/1.8
                  (1.2.5): /Library/Ruby/Gems/1.8
                  (1.2.3): /System/Library/Frameworks/Ruby.framework/ 
Versions/1.8/usr/lib/ruby/gems/1.8

     Web-application framework with template engine, control-flow layer,
     and ORM.

So if you're looking to know where a particular version of a gem is  
installed, it can be better than gem env:

$ gem env
RubyGems Environment:
   - RUBYGEMS VERSION: 1.3.1
   - RUBY VERSION: 1.8.6 (2008-03-03 patchlevel 114) [universal- 
darwin9.0]
   - INSTALLATION DIRECTORY: /Library/Ruby/Gems/1.8
   - RUBY EXECUTABLE: /System/Library/Frameworks/Ruby.framework/ 
Versions/1.8/usr/bin/ruby
   - EXECUTABLE DIRECTORY: /usr/bin
   - RUBYGEMS PLATFORMS:
     - ruby
     - universal-darwin-9
   - GEM PATHS:
      - /Library/Ruby/Gems/1.8
      - /Users/rab/.gem/ruby/1.8
      - /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ 
ruby/gems/1.8
   - GEM CONFIGURATION:
      - :update_sources => true
      - :verbose => true
      - :benchmark => false
      - :backtrace => false
      - :bulk_threshold => 1000
   - REMOTE SOURCES:
      - http://gems.rubyforge.org/

Hopefully, this gives you much more information that you needed ;-)

-Rob

Rob Biedenharn		http://agileconsultingllc.com
Rob / AgileConsultingLLC.com