Multiple Versions of Ruby on Ubuntu #3

This post is from a time before RVM or rbenv you should check out those instead..

I decided it's time to switch to Ruby 1.9 but I still have a couple of Ruby 1.8 projects I need to maintain. That means I need a simple technique for switching back and forth between multiple versions of Ruby. I've experimented with different approaches in the past but I'm not completely satisfied with any of them.

• Multiple Versions of Ruby on Ubuntu #1
• Multiple Versions of Ruby on Ubuntu #2

This time I've decided to use a shell script to update a symbolic link that points to the active version. It's extremely fast and simple.

I started by purging my system of any apt installed Ruby packages.

sudo apt-get remove --purge ruby1.8 ruby1.9

Then I installed Ruby 1.8 from source.

sudo apt-get build-dep ruby1.8
wget -c ftp://ftp.ruby-lang.org/pub/ruby/1.8/ruby-1.8.7-p72.tar.gz
tar -xvzf ruby-1.8.7-p72.tar.gz
cd ruby-1.8.7-p72
./configure --prefix=/opt/ruby-1.8.7-p72 --enable-pthread --enable-shared --enable-openssl --enable-readline --enable-zlib
make
sudo make install
wget -c http://rubyforge.org/frs/download.php/45905/rubygems-1.3.1.tgz
tar -xvzf rubygems-1.3.1.tgz
cd rubygems-1.3.1
sudo /opt/ruby-1.8.7-p72/bin/ruby setup.rb

Then I installed Ruby 1.9 from source.

sudo apt-get build-dep ruby1.9
wget -c ftp://ftp.ruby-lang.org/pub/ruby/1.9/ruby-1.9.1-p0.tar.gz
tar -xvzf ruby-1.9.1-p0.tar.gz
cd ruby-1.9.1-p0/
./configure --prefix=/opt/ruby-1.9.1-p0 --enable-pthread --enable-shared
make
sudo make install

Then I add the following line to the bottom of $HOME/.bashrc

export PATH=/opt/ruby/bin:$PATH

Then I saved the following script in /usr/local/bin/select_ruby

#!/bin/sh

while : # Loop forever
do
cat << !

current = $(/opt/ruby/bin/ruby --version)

Select Option

1. ruby-1.8.6-p368
2. ruby-1.8.7-p72
3. ruby-1.8.7-p160
4. ruby-1.9.1-p0
5. exit

!

echo -n " Your choice? : "
read choice

case $choice in
1) rm -rf /opt/ruby; ln -s /opt/ruby-1.8.6-p368 /opt/ruby;;
2) rm -rf /opt/ruby; ln -s /opt/ruby-1.8.7-p72 /opt/ruby;;
3) rm -rf /opt/ruby; ln -s /opt/ruby-1.8.7-p160 /opt/ruby;;
4) rm -rf /opt/ruby; ln -s /opt/ruby-1.9.1-p0 /opt/ruby;;
5) exit;;
*) echo "\"$choice\" is not valid "; sleep 2 ;;
esac
exit
done

Now to switch I just run the script and select the version I want.

sudo select_ruby

There's a couple of things to be aware of using this approach. Each ruby installation has it's own separate instance of rubygems so gems will have to be installed multiple times. Also since sudo doesn't preserve the users $PATH you will need to use the full path with the gem command; example:

sudo /opt/ruby/bin/gem install rails

Or this fix.