RHEL (binary)
=============

.. contents:: Table of Contents
   :depth: 2
   :local:

This page explains how to install ROS 2 on RHEL from a pre-built binary package.

.. note::

   The pre-built binary does not include all ROS 2 packages.
   All packages in the `ROS base variant <https://ros.org/reps/rep-2001.html#ros-base>`_ are included, and only a subset of packages in the `ROS desktop variant <https://ros.org/reps/rep-2001.html#desktop-variants>`_ are included.
   The exact list of packages are described by the repositories listed in `this ros2.repos file <https://github.com/ros2/ros2/blob/{REPOS_FILE_BRANCH}/ros2.repos>`_.

There are also :doc:`RPM packages <../RHEL-Install-RPMs>` available.

System requirements
-------------------

We currently support RHEL 9 64-bit.

System setup
------------

Set locale
^^^^^^^^^^

.. include:: ../_RHEL-Set-Locale.rst

Enable required repositories
^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The rosdep database contains packages from the EPEL and PowerTools repositories, which are not enabled by default.
They can be enabled by running:

.. code-block:: bash

   sudo dnf install 'dnf-command(config-manager)' epel-release -y
   sudo dnf config-manager --set-enabled crb

.. note:: This step may be slightly different depending on the distribution you are using. Check the EPEL documentation: https://docs.fedoraproject.org/en-US/epel/#_quickstart

Install prerequisites
^^^^^^^^^^^^^^^^^^^^^

There are a few packages that must be installed in order to get and unpack the binary release.

.. code-block:: bash

   sudo dnf install tar bzip2 wget -y

Install development tools (optional)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

If you are going to build ROS packages or otherwise do development, you can also install the development tools:

.. code-block:: bash

   sudo dnf install -y \
     cmake \
     gcc-c++ \
     git \
     make \
     patch \
     python3-colcon-common-extensions \
     python3-flake8-builtins \
     python3-flake8-comprehensions \
     python3-flake8-docstrings \
     python3-flake8-import-order \
     python3-flake8-quotes \
     python3-mypy \
     python3-pip \
     python3-pydocstyle \
     python3-pytest \
     python3-pytest-repeat \
     python3-pytest-rerunfailures \
     python3-rosdep \
     python3-setuptools \
     python3-vcstool \
     wget

   # install some pip packages needed for testing and
   # not available as RPMs
   python3 -m pip install -U --user \
     flake8-blind-except==0.1.1 \
     flake8-class-newline \
     flake8-deprecated

Install ROS 2
-------------

* Go to the `releases page <https://github.com/ros2/ros2/releases>`_
* Download the latest package for RHEL; let's assume that it ends up at ``~/Downloads/ros2-package-linux-x86_64.tar.bz2``.

  * Note: there may be more than one binary download option which might cause the file name to differ.

* Unpack it:

  .. code-block:: bash

       mkdir -p ~/ros2_{DISTRO}
       cd ~/ros2_{DISTRO}
       tar xf ~/Downloads/ros2-package-linux-x86_64.tar.bz2

Install dependencies using rosdep
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.. include:: ../_Dnf-Update-Admonition.rst

.. code-block:: bash

   rosdep install --from-paths ~/ros2_{DISTRO}/ros2-linux/share --ignore-src -y --skip-keys "cyclonedds fastcdr fastrtps ignition-cmake2 ignition-math6 rti-connext-dds-6.0.1 urdfdom_headers"

Install additional RMW implementations (optional)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The default middleware that ROS 2 uses is ``Fast DDS``, but the middleware (RMW) can be replaced at runtime.
See the :doc:`guide <../../How-To-Guides/Working-with-multiple-RMW-implementations>` on how to work with multiple RMWs.

Setup environment
-----------------

Set up your environment by sourcing the following file.

.. code-block:: bash

   # Replace ".bash" with your shell if you're not using bash
   # Possible values are: setup.bash, setup.sh, setup.zsh
   . ~/ros2_{DISTRO}/ros2-linux/setup.bash

Try some examples
-----------------

In one terminal, source the setup file and then run a C++ ``talker``:

.. code-block:: bash

   . ~/ros2_{DISTRO}/ros2-linux/setup.bash
   ros2 run demo_nodes_cpp talker

In another terminal source the setup file and then run a Python ``listener``:

.. code-block:: bash

   . ~/ros2_{DISTRO}/ros2-linux/setup.bash
   ros2 run demo_nodes_py listener

You should see the ``talker`` saying that it's ``Publishing`` messages and the ``listener`` saying ``I heard`` those messages.
This verifies both the C++ and Python APIs are working properly.
Hooray!

Next steps
----------

Continue with the :doc:`tutorials and demos <../../Tutorials>` to configure your environment, create your own workspace and packages, and learn ROS 2 core concepts.

Troubleshoot
------------

Troubleshooting techniques can be found :doc:`here <../../How-To-Guides/Installation-Troubleshooting>`.

Uninstall
---------

1. If you installed your workspace with colcon as instructed above, "uninstalling" could be just a matter of opening a new terminal and not sourcing the workspace's ``setup`` file.
   This way, your environment will behave as though there is no {DISTRO_TITLE} install on your system.

2. If you're also trying to free up space, you can delete the entire workspace directory with:

   .. code-block:: bash

      rm -rf ~/ros2_{DISTRO}