First download the Ruby Version Manager (RVM) installer as follows
$ sudo bash -s stable < <(curl -s https://raw.github.com/wayneeseguin/rvm/master/binscripts/rvm-installer )
RVM requires to add relevant users to it’s group. Open the file like so:
$ sudo vim /etc/group
Edit the ‘rvm’ group (likely the last entry) to look like:
rvm:x:503:your_username
Run the install:
$ cd /usr/local/rvm/bin
$ sudo ./rvm-installer
...
“Upgrade of RVM in /usr/local/rvm/ is complete.”
I needed to reload the RVM to continue, this might not be required:
$ rvm reload
If it shows -bash: rvm: command not found
please close the terminal and start it again to load the RVM.
Now we can install the Ruby version. This will also install rubygems which is always useful…
$ rvm install 1.9.3 --with-openssl-dir=/usr
$ ruby -v
$ rvm use ruby-1.9.3-p327 --default
If you are getting nokogiri error like:
Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.
checking for libxslt/xslt.h… no
libxslt is missing.
then install
$ sudo yum install -y gcc ruby-devel libxml2 libxml2-devel libxslt libxslt-devel
Reference:
http://jamesmcfadden.co.uk/installing-ruby-on-rails-on-centos-5-8/