title: Why does my Cygwin setup tell me Python3.6 not installed?
body: <p>Python 3.6 has been installed (using the Cygwin setup .exe file, update, etc.). The executable is located in <code>/bin/</code> ... or is it located in <code>/usr/bin/</code>? Cygwin <code>ls</code> command shows that <code>/usr/bin</code> exists... but on Windows this directory is non-existent.  Also the contents of both directories are identical, including if I change a filename... but I haven't as yet found a symlink (in <code>/usr</code> or in <code>/</code> ) to explain this!</p>
  
  <p>I'm struggling to get virtualenvwrapper installed (this is part of a preparation required to follow along with a book, TDD With Python).</p>
  
  <p>I just overcame a first hurdle (eventually) by realising I had to install virtualenvwrapper using pip3, not pip! ... I feel like I'm in at the deep end.</p>
  
  <p>So I did:</p>
  
  <pre><code>pip3 install virtualenvwrapper
  echo "source virtualenvwrapper.sh" &gt;&gt; ~/.bashrc
  source ~/.bashrc
  </code></pre>
  
  <p>... then I did </p>
  
  <pre><code>mkvirtualenv --python3=`py -3.6 -c"import sys; print(sys.executable)"` superlists
  </code></pre>
  
  <p>(NB "python3" is the correct name of the symlink which points to the Python3 executable in <code>/bin/</code>; there is a "python" symlink but that points to Python2.7)</p>
  
  <p>And I got:</p>
  
  <blockquote>
    <p>Requested Python version (3.6) not installed<BR>Using base prefix '/usr'
    <BR>New python executable in
    /home/Chris/.virtualenvs/superlists/bin/python3<BR>Also creating
    executable in /home/Chris/.virtualenvs/superlists/bin/python
    <br>Installing setuptools, pip, wheel...done.
    <br>virtualenvwrapper.user_scripts creating
    /home/Chris/.virtualenvs/superlists/bin/predeactivate
    <br>virtualenvwrapper.user_scripts creating
    /home/Chris/.virtualenvs/superlists/bin/postdeactivate
    <br>virtualenvwrapper.user_scripts creating
    /home/Chris/.virtualenvs/superlists/bin/preactivate
    <br>virtualenvwrapper.user_scripts creating
    /home/Chris/.virtualenvs/superlists/bin/postactivate
    <br>virtualenvwrapper.user_scripts creating
    /home/Chris/.virtualenvs/superlists/bin/get_env_details <br>(superlists)</p>
  </blockquote>
  
  <p>Anyone know what's going on? How do I get the system to recognise that Python3.6 is actually installed?</p>
  
  <p><strong>Later</strong> Or... am I being very dense? Maybe making a virtual environment using this module always involves installing a new Python executable?</p>
  
  <p><strong>Later still</strong> I'm still not clear about this... but it isn't stopping me from using <code>virtualenv</code> and <code>virtualenvwrapper</code> and generally getting on with the book. Despite complaining Python doesn't exist the setup appears (as far as I can tell!) to be using the symlinks under the directories in directory .virtualenv/ to one of the Python symlinks in /bin/ ...  </p>