Quieter and works on Debian as well

rbenv-install-system-wide.sh

#!/bin/bash

# rbenv system wide installation script
# Forked from https://gist.github.com/jpfuentes2/2002954
JOB_PID=$$

# Installs rbenv system wide on CentOS 5/6 and Debian, also allows single user installs.
if command -v yum >/dev/null 2>&1; then
  DISTRO="Redhat"
elif command -v aptitude >/dev/null 2>&1; then
  DISTRO="Debian"
fi

# Install pre-requirements
if [ "$DISTRO" == "Redhat" ]; then
  yum install -y -q gcc-c++ patch readline readline-devel zlib zlib-devel libyaml-devel libffi-devel openssl-devel \
    make bzip2 autoconf automake libtool bison iconv-devel git-core > rbenv.yum.$JOB_PID
  if [ `grep -E Package.*'gcc-c\+\+|patch|readline|zlib-|zlib-devel|make|bzip2|autoconf|automake|libtool|bison|git'.*already\ installed\ and\ latest\ version rbenv.yum.$JOB_PID | wc -l` -eq "12" ]; then
    rm -f rbenv.yum.$JOB_PID
  else
    echo "While installing rbenv, yum behaved differently than before groupinstalling devtools"
    echo "Check rbenv.yum.$JOB_PID"
  fi
elif [ "$DISTRO" == "Debian" ]; then
# Needs testing
  aptitude install gcc patch readline readline-dev zlib1g zlib1g-dev libyaml-dev libffi-dev openssl-dev \
    make bzip2 autoconf automake libtool bison iconv-dev git
fi

# Check if Git is installed
hash git 2>&- || { 
  echo >&2 "Error: Git not found. Hint: Try installing the RPMForge or EPEL package repository.";
  exit 1;
}

# Check if /usr/local/rbenv already exists
if [[ -d "/usr/local/rbenv" ]]; then
  echo >&2  "Error: /usr/local/rbenv already exists. Aborting installation.";
  exit 1;
fi

# Install rbenv
git clone git://github.com/sstephenson/rbenv.git /usr/local/rbenv > git.rbenv.$JOB_PID

# Check if clone succesful
if [ $? -gt 0 ]; then
  echo >&2  "Error: Git clone error! See above.";
  exit 1;
else
  rm -f git.rbenv.$JOB_PID
fi

# Add rbenv to the path
echo '# rbenv setup - only add RBENV PATH variables if no single user install found' > /etc/profile.d/rbenv.sh
echo 'if [[ ! -d "${HOME}/.rbenv" ]]; then' >> /etc/profile.d/rbenv.sh
echo '  export RBENV_ROOT=/usr/local/rbenv' >> /etc/profile.d/rbenv.sh
echo '  export PATH="$RBENV_ROOT/bin:$PATH"' >> /etc/profile.d/rbenv.sh
echo '  eval "$(rbenv init -)"' >> /etc/profile.d/rbenv.sh
echo 'fi'  >> /etc/profile.d/rbenv.sh

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

# Install ruby-build:
pushd /tmp
  rm -rf /tmp/ruby-build
  git clone git://github.com/sstephenson/ruby-build.git > git.ruby-build.$JOB_PID

  # Check if clone succesful
  if [ $? -gt 0 ]; then
    echo >&2  "Error: Git clone error! See above.";
    exit 1;
  else
    rm -f git.ruby-build.$JOB_PID
  fi

  cd ruby-build
  ./install.sh > ruby-build.install.log.$JOB_PID
popd

echo '---------------------------------'
echo '    rbenv installed system wide to /usr/local/rbenv'
echo "    For your convenience, ruby-install log is in ruby-build.install.log.$JOB_PID"
echo '    Remember to restart your shell for the changes to take effect!'
echo '---------------------------------'

rbenv-install.sh

#!/bin/bash

# CentOS rbenv installation script
# Forked from https://gist.github.com/1237417

# Installs rbenv to user home on CentOS 5/6.

if [[ -d "${HOME}/.rbenv" ]]; then
  echo >&2  "Error: ${HOME}/.rbenv already exists. Aborting installation.";
  exit 1;
fi

# 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

echo '---------------------------------'
echo "    rbenv installed to $HOME/.rbenv"
echo '    Remember to restart your shell for the changes to take effect!'
echo '---------------------------------'