First, you must check that your Ubuntu accepts restricted, universal, and multiversal repositories. Refer to the Installing ROS Electric – using repositories section if you want to see how to do it.

Normally, Ubuntu is configured to allow these repositories and you won't have problems with this step.

Now we are going to add the URLs from where we can download the code. Note that ROS Fuerte doesn't work for Maverick and Natty, so you must have Ubuntu 10.04, 11.10, or 12.04 on your computer.

For this book we have used Ubuntu 12.04 and it works fine. All the examples have been checked, compiled, and executed in this version of Ubuntu.

Open a new shell and type the following command, as we did before, which should work for any Ubuntu version you have:

$ sudo sh -c 'echo "deb http://packages.ros.org/ros/ubuntu `lsb_release -cs` main" > /etc/apt/sources.list.d/ros-latest.list'

It is important to add the key because with it we can be sure that we are downloading the code from the right place and nobody has modified it.

If you have followed the steps to install ROS Electric, you don't need to do this again as you have already completed this earlier; if not, add the repository using the following command:

$ wget http://packages.ros.org/ros.key -O - | sudo apt-key add –

We are ready to install ROS Fuerte at this point. Before doing something, it is necessary to update all the programs used by ROS. We do it to avoid incompatibility problems.

Type the following command in a shell and wait:

$ sudo apt-get update

Depending on whether you had the system updated or not, the command will take more or less time to finish.

ROS has a lot of parts and installing the full system can be heavy in robots without enough features. For this reason, you can install various versions depending on what you want to install.

For this book, we are going to install the full version. This version will install all the examples, stacks, and programs. This is a good option for us because in some chapters of this book, we will need to use tools, and if we don't install it now, we will have to do it later:

Do not worry if you are installing things that you do not know. In the upcoming chapters, you will learn about everything you are installing and how to use it.

When you gain experience with ROS, you can make basic installations in your robots using only the core of ROS, using less resources, and taking only what you need.

Now that you have installed ROS, to start using it, you must provide Ubuntu with the path where ROS is installed. Open a new shell and type the following command:

$ roscore
roscore: command not found

You will see this message because Ubuntu does not know where to search for the commands. To solve it, type the following command in a shell:

$ source /opt/ros/fuerte/setup.bash

Then, type the roscore command once again, and you will see the following output:

...
started roslaunch server http://localhost:45631/
ros_comm version 1.8.11

SUMMARY
========

PARAMETERS
* /rosdistro
* /rosversion

NODES

auto-starting new master
....

This means that Ubuntu knows where to find the commands to run ROS. Note that if you open another shell and type roscore, it will not work. This is because it is necessary to add this script within the .bashrc file. So, every time you start a new shell, the scripts will run because .bashrc always runs when a shell runs.

Use the following commands to add the script:

$ echo "source /opt/ros/fuerte/setup.bash" >> ~/.bashrc
$ source ~/.bashrc

As mentioned before, only source setup.bash for one ROS distribution. Imagine that you had Electric and Fuerte installed on your computer, and you are using Fuerte as the normal version. If you want to change the version used in a shell, you only have to type the following command:

$ source /opt/ros/electric/setup.bash

If you want to use another version on a permanent basis, you must change the .bashrc file and put the correct script for your version.

ROS has some tools that need to be installed after the principal installation. These tools will help us install dependencies between programs to compile, download, and install packages from ROS. These tools are rosinstall and rosdep. We recommend installing them because we will use them in the upcoming chapters. To install these tools, type the following command in a shell:

$ sudo apt-get install python-rosinstall python-rosdep

Now we have a full installation of ROS on our system. As you can see, only a few steps are necessary to do it.

It is possible to have two or more versions of ROS installed on our computer. Furthermore, you can install ROS on a virtual machine if you don't have Ubuntu installed on your computer.

In the next section, we will explain how to install a virtual machine and use a drive image with ROS. Perhaps this is the best way to get ROS for new users.