Tag Archives: Ruby Gem

Ruby Gems : Lucy In The Sky With Gems

Python has its eggs, Java has its jars and ruby has its gems. So a gem is a ruby package, containing some library or executable program. In the previous two chapters about RVM and Rbenv I installed rails using the gem command. Since ruby 1.9, Ruby Gems comes with ruby. So, how to use it?

  1. You can list all the available gems, hosted on RubyGems.org with:

    gem query --remote (gem q -r)
    or
    gem list -r


  2. You can search for remote gems with:
    gem query --remote --name-matches <name>
    or
    gem search -r <name>
    or
    gem search <name>
    or
    gem sea <name>
  3. You can install a gem using:
    gem install --remote <name>
    or
    gem install <name>
    or
    gem ins <name>
  4. You can install a given version of a gem using:
    gem install --remote <name> --version <version>
    or
    gem install <name> --version <version>
    or
    gem ins <name> --version <version>
    or like that
    gem install <name>-<version>

    For versions you can use  operators :

    gem install <name> --version "= 0.1.3"  
    
    All operators:
      =  Equals version
      != Not equal to version
      >  Greater than version
      <  Less than version
      >= Greater than or equal to
      <= Less than or equal to
      ~> Approximately greater than 

    To see all available versions of a gems:

    gem search -a <name>
    or
    gem list -r -a
  5. To see the locally installed gems:
    gem list (-l)
    or
    gem query -l (--local)

    To search in the locally installed gems for given gem:

    gem search -l <name>

    A detailed information for an installed gem:

    gem specification <name>

    This can be executed with the ‘-r’ option for remote gem.
    A cool feature is to run

    gem server

    And to use your browser, opening http://localhost:8808 to browse detailed information for your installed gems.

  6. To uninstall a gem:
    gem uninstall <name>
  7. You can install gems with options like ‘–no-rdoc or ‘no-ri’, see all available using:
    gem help install

    You can put a .gemrc file in your home with some commands and settings to be used with Ruby Gems. The file should look like this:

      gem:  --local --no-rdoc --run-tests
      gempath:
        - /usr/share/rubygems
        - /home/meddle/.stuff

    Read for more here http://docs.rubygems.org/read/chapter/11

I think this is a good manual for the tool, we will use it a lot in the up-coming posts.

Useful Links:

  1. Ruby Gems site – http://rubygems.org
  2. Ruby Gems docs – http://docs.rubygems.org
  3. Manual at http://www.ruby-lang.org – http://www.ruby-lang.org/en/libraries
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