A better idea would be to use [RVM](http://beginrescueend.com/rvm/).

Installing RVM as a single-user is easy (multi-user instructions can be
found on their site):

  1. Download `curl` and `git-core` from your package manager.

  2. Run the following command (super user permission not needed):
         $ bash -s stable < <(curl -ss \
           https://raw.github.com/wayneeseguin/rvm/master/binscripts/rvm-installer)

  3. Load RVM into your bash file:
         $ echo '[[ -s "$HOME/.rvm/scripts/rvm" ]] \
           && . "$HOME/.rvm/scripts/rvm" >> ~/.bash_profile

  4. Reload your bash file by restarting the terminal or by running
     `source ~/.bashrc`.

  5. Test for rvm with `type rvm | head -1`.  It should output `rvm is a
     function`.

Installing Ruby 1.9.3:

  1. Make sure all dependencies are met by running `rvm requirements`.

  2. Install Ruby 1.9.3 with `rvm install ruby-1.9.3-head`.

  3. Use Ruby 1.9.3 by running `rvm use ruby-1.9.3-head`.  You can also
     set Ruby 1.9.3 to the default ruby installation by running `rvm use
     ruby-1.9.3-head --default`.

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