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Ruby Interpreter

The Ruby Interpreter is required in order to use:

  • MRvcmt, a graphical user interface (GUI) to the configuration management tool (CMT).
  • FRED, the GLAST event display tool.


  1. If you have a Windows machine, download the Ruby Interpreter from the RubyForge website using the site's "One-Click Installer". Important! Fred will not run without ruby's extension for the expat add-on; this add-on, along with others, is included when you use the installer.

Troubleshooting Tip – Windows machines only; does not apply to Linux: Verify that there is see a libexpat.dll in your ruby's bin directory. At the time this was written, the procedures in this section were run using Ruby 1.8.6, and it is strongly recommended that Windows users use this version if possible.

Note: Fred was also tested with an earlier version, Ruby v1.8.2-15, which is no longer available from the Ruby website. It is now believed that the inability to use Fred with some versions of Ruby may have been due to the failure to include the expat add-on during the installation.

  1. Test your Ruby Installation as follows:
    1. Open a DOS window.
    1. At the DOS prompt, enter:

      ruby --version

    Your installation was successful if you see something similar to:

    ruby 1.8.2 (2004-07029) [i386-mswin32]


If you have a Linux machine, the Ruby Interpreter utility should already be installed on your system. To verify, enter (from the command line):

    ruby --version

  • If ruby is installed, the response will be similar to:
  • jrb@noric13 $ ruby --version
    ruby 1.8.1 (2003-12-25) [i686-linux]

  • If ruby is not installed:
    1. Download the Ruby Interpreter from the Ruby website and uncompress it.
    1. To install it, enter:

    ./configure --prefix=myInstallDirectory

    (where "myInstallDirectory" is an absolute path)

    > make
    > make install

    1. To make it accessible for csh or tcsh shell, enter:

    setenv PATH ${PATH}:myInstallDirectory

    Note: Make an analogous path for the bash shell.


Last updated by: Chuck Patterson 04/19/2010