title: How to setup ROS environment variable on Ubuntu 20.04?
body: <p>I tried following <a href="http://wiki.ros.org/melodic/Installation/Ubuntu" rel="nofollow noreferrer">this</a> guide to install ROS, but even after adding ROS source.list and its key </p>
  
  <pre><code>sudo apt install ros-melodic-desktop-full
  </code></pre>
  
  <p>gave error.</p>
  
  <pre><code>E: Unable to locate package ros-melodic-desktop-full
  </code></pre>
  
  <p>Then I ran this command</p>
  
  <pre><code>sudo apt search ros
  </code></pre>
  
  <p>to see if any such package exists. I couldn't find <code>ros-melodic-desktop-full</code> but I found another similar package <code>ros-desktop-full</code>.
  So I installed it instead. The installation went smooth without giving any errors. </p>
  
  <p>Next step in the guide is to set-up ROS environment variable, but I have no such directory</p>
  
  <pre><code>/opt/ros
  </code></pre>
  
  <p>So how do I setup the environment variable?</p>
  
  <p><strong>P.S.</strong></p>
  
  <p>I also installed some tools and dependencies with this command</p>
  
  <pre><code>sudo apt install python3-rosdep python3-rosinstall python3-rosinstall-generator python3-wstool build-essential
  </code></pre>
  
  <p>and initialized <code>rosdep</code></p>
  
  <pre><code>sudo rosdep init
  rosdep update
  </code></pre>