rubygems - ruby gem not found although it is installed

Question

I found some similar problems here on SO, but none seem to match my case (sorry if I overlooked). Here's my problem: I installed oauth-plugin gem to ruby gems dir, but trying to use it in rails app tells me that it's not being found. Here's the output of relevant commands:

Installation

% s gem install oauth-plugin
Successfully installed oauth-plugin-0.3.14
1 gem installed
Installing ri documentation for oauth-plugin-0.3.14...
Installing RDoc documentation for oauth-plugin-0.3.14...

gem which oauth-plugin output:

% gem which oauth-plugin
/usr/lib/ruby/gems/1.8/gems/oauth-plugin-0.3.14/lib/oauth-plugin.rb

gem env output:

% gem env
RubyGems Environment:
  - RUBYGEMS VERSION: 1.3.6
  - RUBY VERSION: 1.8.7 (2009-12-24 patchlevel 248) [i686-darwin10.2.0]
  - INSTALLATION DIRECTORY: /usr/lib/ruby/gems/1.8
  - RUBY EXECUTABLE: /usr/bin/ruby
  - EXECUTABLE DIRECTORY: /usr/bin
  - RUBYGEMS PLATFORMS:
    - ruby
    - x86-darwin-10
  - GEM PATHS:
     - /usr/lib/ruby/gems/1.8
     - /Users/eimantas/.gem/ruby/1.8
  - GEM CONFIGURATION:
     - :update_sources => true
     - :verbose => true
     - :benchmark => false
     - :backtrace => true
     - :bulk_threshold => 1000
     - :gem => ["--no-ri", "--no-rdoc"]
     - :sources => ["http://gems.ruby.lt/", "http://rubygems.org/"]
  - REMOTE SOURCES:
     - http://gems.ruby.lt/
     - http://rubygems.org/

Doing ls -l /usr/lib/ruby shows this:

% ls -l /usr/lib/ruby     
lrwxr-xr-x  1 root  wheel  76 Aug 14  2009 /usr/lib/ruby -> ../../System/Library/Frameworks/Ruby.framework/Versions/Current/usr/lib/ruby

And the gem in question is in intended location.

Here's the error that rails give me when I try running $ rake spec

Missing these required gems:
  oauth-plugin   = 0.3.14

You're running:
  ruby 1.8.7.173 at /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby
  rubygems 1.3.6 at /Users/eimantas/.gem/ruby/1.8, /Library/Ruby/Gems/1.8, /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8

Run `rake gems:install` to install the missing gems.

This is not a single gem that is not being found by rubygems (although it's located where it should be). Any guidance towards the solution is much appreciated.

Answer 1

You have two different versions of Ruby installed. First is in:

/usr/bin/ruby

and second one is in:

/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby

The problem is that one is used in command line (i.e. to install gems) and another is used by web server to run Rails.

Since your web server is using second Ruby version one solution would be to install gem using that Ruby version. Alternatively, you can tell your web server to use different Ruby version - depending on which server you are using this can be achieved in different ways.