We assume that you have a desktop system with Ubuntu 16.04 or Ubuntu 18.04 long-term support (LTS) installed, with an Intel Corei5 processor @3.2 GHz and 8GB of RAM, or similar. Furthermore, it is necessary to have a basic knowledge and understanding of Linux and command tools. If you need to refresh your memory or learn about these tools, you can find a lot of relevant resources on the internet, or you can find books on these topics instead.

In this section, we will discuss the ROS distribution and the corresponding supported operating system, which will guide help us in selecting the right combination, depending upon our requirements.

An ROS distribution is a versioned set of ROS packages. These are very similar to Linux distributions. The purpose of the ROS distributions is to let developers work against a relatively stable code base until they are ready to set up forward. Each distribution maintains a stable set of core packages up to the end of life (EOL) of the distribution.

The latest recommended ROS distribution is Kinectic Kame, which will get support up to May 2021, however, the latest ROS distribution is Melodic Morenia, which was released on 23rd May 2018, and will be supported up to May 2023. One of the problems with this latest ROS distribution is that most of the packages will not be available on it because it will take time to migrate them from the previous distribution, so we do not recommend this.

The list of distributions to use can be found on the ROS website (http://wiki.ros.org/distributions):

ROS is fully compatible with the Ubuntu operating system by design. Moreover, the ROS distributions are planned according to Ubuntu releases. Nevertheless, they are partially supported by Ubuntu ARM, Gentoo, macOS X, Arch Linux, and OpenEmbedded. The following table shows ROS distributions and the corresponding versions of the supported operating systems:

As we have discussed in the previous section, there are several ROS distributions available to download and install. Therefore, we recommend you select the LTS release, which is stable and getting maximum support.

However, if the latest features of ROS are required, you could go for the latest version, but you will not get the latest complete packages immediately after release because of the migration period from one distribution to another.

In this book, we are using two LTS distributions, ROS Kinetic and ROS Melodic, for all experiments.

The following screenshot shows a choice of ROS installations:

We can get the complete installation instructions for each distribution from the ROS website (http://www.ros.org/). Afterward, navigate to Getting Started | Install. It will show a screen listing, as shown in the preceding diagram, for the latest ROS distributions.

In the following section, we will go through the instructions for installing the latest ROS distribution.

To configure the Ubuntu repository, first search for Software & Updates in the Ubuntu Search Toolbar and enable the restricted, universe, and multiverse Ubuntu repositories, as shown in the following screenshot:

The next step is to set up the desktop system to accept software from packages.ros.org. The details of the ROS repository server have to be added into /etc/apt/source.list:

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

Whenever a new repository is added to the Ubuntu repository manager, we have to make it trusted to validate the origin of the packages by adding the keys. The following key should be added to Ubuntu before starting the installation, which will ensure the download comes from an authorized server:

$ sudo apt-key adv --keyserver hkp://ha.pool.sks-keyservers.net:80 --recv-key 421C365BD9FF1F717815A3895523BAEEB01FA116

Now, we are prepared to install the ROS packages on Ubuntu. The first step is to update the list of packages by using the following command:

$ sudo apt-get update

There are many different libraries and tools in ROS, however, we will provide four default configurations to get you started:

• Desktop-Full install (recommended):

$ sudo apt-get install ros-kinetic-desktop-full

• Desktop install:

$ sudo apt-get install ros-kinetic-desktop

• ROS-Base:

$ sudo apt-get install ros-kinetic-ros-base

• Individual Package:

$ sudo apt-get install ros-kinetic-PACKAGE

Now, we are ready to install the ROS packages on Ubuntu 18.04 LTS. The first step is to update the list of packages by using the following command:

$ sudo apt-get update

There are many different libraries and tools in ROS, however, we will provide four default configurations to get you started:

• Desktop-Full Install (recommended):

$ sudo apt-get install ros-melodic-desktop-full

• Desktop Install:

$ sudo apt-get install ros-melodic-desktop

• ROS-Base:

$ sudo apt-get install ros-melodic-ros-base

• Individual Package:

$ sudo apt-get install ros-melodic-PACKAGE

Before using ROS, you have to initialize rosdep, which enables you to easily install system dependencies for sources you want to compile, and also is required to run some core components in ROS:

$ sudo rosdep init
$ rosdep update

Good! We have completed the ROS installation. The ROS scripts and executables are mostly installed to /opt/ros/<ros_version>.

To get access to these scripts and executables, the ROS environment variables need to be added to the bash session. We have to source the following bash file for ROS Kinetic:

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

ROS Melodic requires the following:

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

It's convenient if the ROS environment variables are automatically added to the bash session every time a new shell is launched.

For ROS Kinetic, use the following:

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

For ROS Melodic, use the following:

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

If we have more than one ROS distribution installed, ~/.bashrc must only source setup.bash for the version we are currently using:

$ source /opt/ros/<ros_version>/setup.bash

Moreover, rosinstall is a frequently used command-line tool in ROS that is distributed separately. It enables us to easily download several source trees for the ROS packages with the single command.

This tool is based on Python, and can be installed using the following command:

$ sudo apt-get install python-rosinstall

The ROS packages are built by the ROS build farm. We can check the status of individual packages at http://repositories.ros.org/status_page/.

Congratulations! We are done with the ROS installation. We will execute the following command to check whether the installation is correct.

Open a new terminal to run roscore:

$ roscore

This is followed by a turtlesim node in another terminal:

$ rosrun turtlesim turtlesim_node

If everything is correct, we will get the following screen: