Multiple Versions of Ruby On Ubuntu

edit: moved install from $HOME to /opt.

With Ruby 1.9 out there's the obvious possiblitity some people will want to run multiple versions of Ruby so I thought I'd share this.

My goal is to have the Ubuntu Ruby packages installed along side the most current releases of 1.8 and 1.9

First I'll install using apt to create my default ruby install.

$> sudo apt-get install ruby irb ri rdoc libruby-extras rubygems ruby1.8-dev
$> sudo gem install rake

Next I'll install the most current release packages of 1.8 and 1.9 in to /opt/ruby1.8.6 and /opt/ruby1.9.0 respectively.

Before doing that I'll make sure I have all the necessary build dependencies for both packages

$> sudo apt-get build-dep ruby1.8 ruby1.9

Next I downloaded both packages into a working directory and decompress them

$>mkdir temp; cd temp
$>wget ftp://ftp.ruby-lang.org/pub/ruby/1.8/ruby-1.8.6-p111.tar.gz
$>tar -xvzf ruby-1.8.6-p111.tar.gz
$>wget ftp://ftp.ruby-lang.org/pub/ruby/1.9/ruby-1.9.0-0.tar.gz
$>tar -xvzf ruby-1.9.0-0.tar.gz

Next I build each of the packages.

$> cd ruby-1.8*
$> ./configure --prefix=/opt/ruby1.8 --program-suffix=1.8.6
$> sudo make && make install
$> cd ../ruby-1.9*
$> ./configure --prefix=/opt/ruby1.9 --program-suffix=1.9.0
$> sudo make && make install

Ruby 1.8 doesn't have built in support for gems like Ruby 1.9 so we'll have to install it.

$> wget http://rubyforge.org/frs/download.php/29548/rubygems-1.0.1.tgz
$> tar -xvzf rubygems-1.0.1.tgz
$> cd rubygems*
$> sudo /opt/ruby1.8.6/bin/ruby1.8.6 setup.rb

Notice that I specified the entire path to the ruby executable while installing RubyGems for 1.8.6

The next thing I do is create some symbolic links to make life a little bit easier.

$> sudo ln -s /opt/ruby1.8.6/bin/* /usr/local/bin
$> sudo ln -s /opt/ruby1.9.0/bin/* /usr/local/bin

Now test things a bit to make sure everything makes sense

$> which ruby
>> /usr/bin/ruby
$> gem env
>> ....
>> GEM PATH: /var/lib/gems/1.8
>> ....

$> which ruby1.8.6
>> /usr/local/bin/ruby1.8.6
$> gem1.8.6 env
>> ....
>> GEM PATH: /opt/ruby1.8.6/lib/ruby/gems/1.8
>> ....

$> which ruby1.9.0
>> /usr/local/bin/ruby1.9.0
$> gem1.9.0 env
>> ....
>> GEM PATH: /opt/ruby1.9.0/lib/ruby/gems/1.8
>> ....

A couple of things to watch out for:

• Make sure you don't have any RubyGems environment variables set. They're not needed for any of this and most likley will mess something up.
  
• Don't install any gems until after you create your symbolic links or the executable commands may clobber each other.
• You have to specify the full path to an executable gem because they don't play nicely with program suffixes. So for example '/opt/ruby1.8.6/bin/rake' will do what you expect but just typing 'rake' may not.

One last little tidbit. I'm not sure if the Ubuntu RubyGems packages deal with fixing up the $PATH yet? Regardless the fix is easy; add this little bit of code to the bottom of your ~/.bashrc file

if [ -d /var/lib/gems/1.8/bin ]; then
PATH=/var/lib/gems/1.8/bin:"${PATH}"
fi
export PATH

Customizing Debian Packages

Debian's packaging system makes it really easy to modify packages if you want to. In this little howto I modify ffmpeg to add MP3 support but the process can easily be adapted to any package.

First create a work directory and drop down into it. This is just to make cleanup easy.

$> mkdir temp; cd temp

Then make sure the ffmpeg build dependencies are installed

$> sudo apt-get build-dep ffmpeg

Then download the source package

$> apt-get source ffmpeg

Then install the extra (codec) libraries we're adding support for

$> sudo apt-get install liblame-dev libfaad2-dev libfaac-dev libxvidcore4-dev

Then drop down into the ffmpeg source directory

$> cd ffmpeg*

Now you will have to edit the first line of the the debian/changelog and modify the package version. If you don't system updates will want to 'replace' your modified package. The first line should look something like this:

ffmpeg (3:0.cvs20070307-5ubuntu4) gutsy; urgency=low

. You will want append something at the end of the part in parentheses. In my case I use:

ffmpeg (3:0.cvs20070307-5ubuntu4-mg1) gutsy; urgency=low

It's my initials followed by a revision number.

Once you've modified the change log you can build the package but before we do we set an environment variable used by the build scripts that indicates we want the 'risky' libraries included.

$> DEB_BUILD_OPTIONS=risky && fakeroot debian/rules binary

Now we just need to install the packages. The packages were placed up one directory during the build process so we just move up and install.

$> cd .. && sudo dpkg -i *.deb

Now we just clean up after ourselves

$> cd .. && rm -rf temp