title: Cannot install catkin on clean ubuntu 18
body: <p>I have a super clean installation of ubuntu 18.04: i downloaded it jesterday, installed it today and literally the third thing i installed was the <code>ros-melodic-destkop-full</code> suite/package, the first two being an update/upgrade to the system via update manager, and getting telegram.</p>
  
  <p>Now the point here is that the package 
  <code>catkin</code>
   wasn't installed. Note that catkin_init_workspace and catkin_* commands still exists, and it is what used in ros guides, but not in our project. In our project we use catkin build and catkin make (I know we might be wrong, I don't know WHY we might be wrong in doing this, but just for the sake of asking the question).</p>
  
  <p>It happened on other machines. Actually, on every single other machines, both with new and already-in-use os (always with Ubuntu 18.04 though).</p>
  
  <p>Doing a bunch of random commands like <code>purge ros* remove *catkin* python-catkin-*</code> and then reinstalling ros just like in the official ros guide does in the end, with some prays, work.</p>
  
  <p>i know that ros installation gives problem to almost everbody, but does anyone knows the reason, a possible solution to this? Where is the problem? Ros sided or Ubuntu sided?</p>
  
  <p>(NOTE: when i try sudo apt install catkin, it tells me that it needs the pacakge python-catkin-tools, and it's not going to be installed, although it is already installed and updated).</p>