Usando Rbenv

Simple Ruby Version Management

Antes da instalação é preciso instalar dependências

#aptitude install curl build-essential libssl-dev libreadline6 libreadline6-dev zlib1g-dev zlib1g libpq-dev

Debian 7 - Wheezy (testing)

Instalando o rbenv

#aptitude install rbenv

Debian 6 - Squeeze (stable)

Baixe o pacote rbenv

#wget http://ftp.us.debian.org/debian/pool/main/r/rbenv/rbenv_0.1.2+git20100922-1_all.deb
#sudo dpkg -i rbenv_0.1.2+git20100922-1_all.deb

Configure o alternatives conforme descrito em http://krnjevic.com/wp/?p=209

Passos de uso comum

$ ruby -v
ruby 1.8.7 (2010-08-16 patchlevel 302) [x86_64-linux]
$ rbenv init 
# Load rbenv automatically by adding
# the following to ~/.bashrc:

eval "$(rbenv init -)" 
$ echo 'eval "$(rbenv init -)"' >> ~/.bashrc
$ source ~/.bashrc
$ rbenv versions
$ rbenv alternatives 
$ rbenv versions
  1.8.7-debian
  1.9.2-debian
    

Instalando o ruby-build

$ git clone git://github.com/sstephenson/ruby-build.git
$ cd ruby-build
$ sudo ./install.sh
$ sudo chmod 755 -R /usr/local/lib/site_ruby/ /usr/local/share/ruby-build/ /usr/local/bin/r*

$ rbenv-install 
usage: rbenv install VERSION
       rbenv install /path/to/definition

Available versions:
  1.8.6-p420
  1.8.7-p249
  1.8.7-p334
  1.8.7-p352
  1.9.1-p378
  1.9.2-p180
  1.9.2-p290
  1.9.3-dev
  1.9.3-p0
  1.9.3-preview1
  1.9.3-rc1
  2.0.0-dev
  jruby-1.6.3
  jruby-1.6.4
  jruby-1.6.5
  jruby-1.7.0-dev
  maglev-1.0.0
  rbx-1.2.4
  rbx-2.0.0-dev
  ree-1.8.6-2009.06
  ree-1.8.7-2010.02
  ree-1.8.7-2011.03

$ rbenv-install 1.9.3-p0
...

$ rbenv global 1.9.3-p0
$ ruby -v
ruby 1.9.3p0 (2011-10-30 revision 33570) [x86_64-linux]        

Fonte

http://wiki.debian.org/Ruby | Instalar no Ubuntu 11.10