ubuntu下安装rails 3.0

1.sudo apt-get update
  we have the latest sources on our box so that we don’t run into any package-related issues, such as not being able to install some packages.
2. sudo apt-get install build-essential git-core curl
  we’re going to install Git (a version control system) and curl which are both required to install and use RVM, and build-essential which is required to compile Ruby versions, amongst other compilable things.
3.bash < <( curl http://rvm.beginrescueend.com/releas/rvm-install-head)
  With git-core and curl installed we’ll be able to install RVM with up command。
  Once that’s done, we’re going to need to add a line to ~/.bashrc file (the file responsible for setting up our bash session) which will load RVM:
  echo '[[ -s "$HOME/.rvm/scripts/rvm" ]] && source "$HOME/.rvm/scripts/rvm"' >> ~/.bashrc
  Then we’ll need to reload the ~/.bashrc file which we can do with this small command:
   . ~/.bashrc
  The next command we run will tell us what other packages we need to install for Ruby to work:
  rvm notes
4.sudo aptitude install build-essential bison openssl libreadline6 libreadline6-dev curl git-core zlib1g
zlib1g-dev libssl-dev libyaml-dev libsqlite3-0 libsqlite3-dev sqlite3 libxml2-dev libxslt-dev autoconf
5. rvm install 1.9.2
6.rvm --default use 1.9.2
7.gem install rails