RVM(Ruby Version Manager)によるRubyのインストール

$ curl -L https://get.rvm.io | bash -s stable

  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 20511  100 20511    0     0  15562      0  0:00:01  0:00:01 --:--:-- 15562
Downloading https://github.com/wayneeseguin/rvm/archive/stable.tar.gz

Installing RVM to /home/redmine/.rvm/
    Adding rvm PATH line to /home/redmine/.profile /home/redmine/.bashrc /home/redmine/.zshrc.
    Adding rvm loading line to /home/redmine/.bash_profile /home/redmine/.zlogin.
Installation of RVM in /home/redmine/.rvm/ is almost complete:

  * To start using RVM you need to run `source /home/redmine/.rvm/scripts/rvm`
    in all your open shell windows, in rare cases you need to reopen all shell windows.

# redmine,
#
#   Thank you for using RVM!
#   We sincerely hope that RVM helps to make your life easier and more enjoyable!!!
#
# ~Wayne, Michal & team.

In case of problems: http://rvm.io/help and https://twitter.com/rvm_io

  * WARNING: You have '~/.profile' file, you might want to load it,
    to do that add the following line to '/home/redmine/.bash_profile':

      source ~/.profile

インストールが完了したら rvm を読み込む。

$ source ~/.rvm/scripts/rvm

$ sudo yum install readline readline-devel ncurses ncurses-devel gdbm gdbm-devel glibc-devel tcl-devel tk-devel libX11-devel autoconf gcc unzip openssl-devel db4-devel byacc patch libyaml-devel libffi-devel gcc-c++ patch automake libtool bison

$ rvm install 2.0.0

Searching for binary rubies, this might take some time.
No binary rubies available for: centos/6/x86_64/ruby-2.0.0-p451.
Continuing with compilation. Please read 'rvm help mount' to get more information on binary rubies.
Checking requirements for centos.
Requirements installation successful.
Installing Ruby from source to: /home/redmine/.rvm/rubies/ruby-2.0.0-p451, this may take a while depending on your cpu(s)...
ruby-2.0.0-p451 - #downloading ruby-2.0.0-p451, this may take a while depending on your connection...
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 10.2M  100 10.2M    0     0  7785k      0  0:00:01  0:00:01 --:--:-- 8234k
ruby-2.0.0-p451 - #extracting ruby-2.0.0-p451 to /home/redmine/.rvm/src/ruby-2.0.0-p451...
ruby-2.0.0-p451 - #applying patch /home/redmine/.rvm/patches/ruby/changeset_r45225.diff.
ruby-2.0.0-p451 - #applying patch /home/redmine/.rvm/patches/ruby/changeset_r45240.diff.
ruby-2.0.0-p451 - #applying patch /home/redmine/.rvm/patches/ruby/ssl_no_ec2m.patch.
ruby-2.0.0-p451 - #configuring.................................................
ruby-2.0.0-p451 - #post-configuration.
ruby-2.0.0-p451 - #compiling..............................................................................
ruby-2.0.0-p451 - #installing.............................
ruby-2.0.0-p451 - #making binaries executable..
ruby-2.0.0-p451 - #downloading rubygems-2.2.2
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100  404k  100  404k    0     0  1267k      0 --:--:-- --:--:-- --:--:-- 2073k
No checksum for downloaded archive, recording checksum in user configuration.
ruby-2.0.0-p451 - #extracting rubygems-2.2.2...
ruby-2.0.0-p451 - #removing old rubygems.........
ruby-2.0.0-p451 - #installing rubygems-2.2.2...............
ruby-2.0.0-p451 - #gemset created /home/redmine/.rvm/gems/ruby-2.0.0-p451@global
ruby-2.0.0-p451 - #importing gemset /home/redmine/.rvm/gemsets/global.gems.............................................................
ruby-2.0.0-p451 - #generating global wrappers.........
ruby-2.0.0-p451 - #gemset created /home/redmine/.rvm/gems/ruby-2.0.0-p451
ruby-2.0.0-p451 - #importing gemsetfile /home/redmine/.rvm/gemsets/default.gems evaluated to empty gem list
ruby-2.0.0-p451 - #generating default wrappers.........
ruby-2.0.0-p451 - #adjusting #shebangs for (gem irb erb ri rdoc testrb rake).
Install of ruby-2.0.0-p451 - #complete
Please be aware that you just installed a ruby that requires 2 patches just to be compiled on an up to date linux system.
This may have known and unaccounted for security vulnerabilities.
Please consider upgrading to ruby-2.1.1 which will have all of the latest security patches.
Ruby was built without documentation, to build it run: rvm docs generate-ri

Ruby 2.0.0 をデフォルトにする。

$ rvm use 2.0.0 --default
Using /home/redmine/.rvm/gems/ruby-2.0.0-p451

$ ruby -v
ruby 2.0.0p451 (2014-02-24 revision 45167) [x86_64-linux]