rbenv install and system wide install on Ubuntu 10.04 LTS.

rbenv-install-system-wide.sh

#!/bin/bash
# Update, upgrade and install development tools:
apt-get update
apt-get -y upgrade
apt-get -y install build-essential
apt-get -y install vim git-core curl zlib1g-dev libreadline-dev libssl-dev

# Install rbenv
if [ ! -d "/usr/local/rbenv" ]; then
  git clone git://github.com/sstephenson/rbenv.git /usr/local/rbenv
fi

# Add rbenv to the path:
echo '# rbenv setup' > /etc/profile.d/rbenv.sh
echo 'export RBENV_ROOT=/usr/local/rbenv' >> /etc/profile.d/rbenv.sh
echo 'export PATH="$RBENV_ROOT/bin:$PATH"' >> /etc/profile.d/rbenv.sh
echo 'eval "$(rbenv init -)"' >> /etc/profile.d/rbenv.sh

chmod +x /etc/profile.d/rbenv.sh
source /etc/profile.d/rbenv.sh

# Install ruby-build:
if [ ! -f "/usr/local/bin/ruby-build" ]; then
  pushd /tmp
    git clone git://github.com/sstephenson/ruby-build.git
    cd ruby-build
    ./install.sh
  popd
fi

# Install Ruby 1.9.3-p125:
rbenv install 1.9.3-p125
rbenv global 1.9.3-p125

# Rehash:
rbenv rehash

rbenv-install.sh

# Update, upgrade and install development tools:
apt-get update
apt-get -y upgrade
apt-get -y install build-essential
apt-get -y install git-core

# Install rbenv:
git clone git://github.com/sstephenson/rbenv.git ~/.rbenv

# Add rbenv to the path:
echo 'export PATH="$HOME/.rbenv/bin:$PATH"' >> .bash_profile
echo 'eval "$(rbenv init -)"' >> .bash_profile
source ~/.bash_profile

# Install ruby-build:
pushd /tmp
  git clone git://github.com/sstephenson/ruby-build.git
  cd ruby-build
  ./install.sh
popd

# Install Ruby 1.9.3-p0:
rbenv install 1.9.3-p0
rbenv global 1.9.3-p0

# Rehash:
rbenv rehash