Getting and Installing Ruby

No matter how wonderful Ruby is, there isn't much you can do with it if it is not installed on your computer system. In this chapter we will cover the download and installation of Ruby on a variety of different operating systems, specifically Linux, UNIX, Windows and Mac OS X.

Ruby is itself written in the C programming language. This means that either a binary distribution for your chosen operating system and hardware platform needs to be installed, or the Ruby sources need to be downloaded and compiled on your target system. Whilst compiling Ruby yourself might be fun, it usually makes more sense to simply download and install one of the many pre-built Ruby packages rather than attempt to build your own. In this chapter we will cover installing pre-built Ruby packages on each platform.

Installing Ruby on Linux

There are a number of different Linux distributions available today and it makes sense to install the Ruby package built specifically for your chosen Linux flavor. The best way to do this is to use the standard package manager for that particalur Linux.

Ruby on Red Hat Enterprise and Fedora Linux

Red Hat Enterprise Linux and Fedora Linux both use the YUM installation manager and rpm. The first step is to verify if Ruby is installed. This can be achieved using the following rpm command. In this example, Ruby is not yet installed:

rpm -q ruby
package ruby is not installed

If Ruby is not installed, it can be installed using the yum update manager. This needs to be performed as root so the superuser password will be required in the following steps:

su -
yum install ruby

The yum tool will locate the ruby package and any other packages on which Ruby is dependent and prompt you to install the packages:

=============================================================================
Installing:
 ruby                    i386       1.8.1-7.EL4.8    base              156 k
Installing for dependencies:
 ruby-libs               i386       1.8.1-7.EL4.8    base              1.5 M

Transaction Summary
=============================================================================
Install      2 Package(s)
Update       0 Package(s)
Remove       0 Package(s)
Total download size: 1.6 M
Is this ok [y/N]:

Enter 'y' to download and install the required packages:

Downloading Packages:
(1/2): ruby-1.8.1-7.EL4.8 100% |=========================| 156 kB    00:10
(2/2): ruby-libs-1.8.1-7. 100% |=========================| 1.5 MB    01:23
Running Transaction Test
Finished Transaction Test
Transaction Test Succeeded
Running Transaction
  Installing: ruby-libs                    ######################### [1/2]
  Installing: ruby                         ######################### [2/2]

Installed: ruby.i386 0:1.8.1-7.EL4.8
Dependency Installed: ruby-libs.i386 0:1.8.1-7.EL4.8
Complete!

Once the installation is complete, you may re-run the rpm command to verify the package is now installed:

rpm -q ruby
ruby-1.8.1-7.EL4.8

Dependencies Resolved </pre>

Ruby on Ubuntu and Debian Linux

Debian, Ubuntu and other Debian derived Linux distributions use the apt-get tool to manage package installation. If you are running Ubuntu Linux and get the following output from the ruby command, you need to install Ruby:

$ ruby
The program 'ruby' is currently not installed.  You can install it by typing:
sudo apt-get install ruby
-bash: ruby: command not found

To install ruby, simply run the apt-get command:

sudo apt-get install ruby

The apt-get tool will display output listing any other packages required by Ruby (better known as dependencies):

Reading package lists... Done
Building dependency tree
Reading state information... Done
The following extra packages will be installed:
  libruby1.8 ruby1.8
Suggested packages:
  ruby1.8-examples rdoc1.8 ri1.8
The following NEW packages will be installed:
  libruby1.8 ruby ruby1.8
0 upgraded, 3 newly installed, 0 to remove and 135 not upgraded.
Need to get 1769kB of archives.
After unpacking 6267kB of additional disk space will be used.
Do you want to continue [Y/n]?