title: Which $path is needed so g++/pybind11 could locate Python.h?
body: <p>I started using <code>pybind11</code> (on <em>Ubuntu 16.04</em> with <em>Python 2.7</em>).</p>
  
  <p>To test the waters, I created a do-nothing wrapper around my c++ library. Alas, the compilation is unable to find <code>Python.h</code>:</p>
  
  <pre><code>$ g++ -std=c++0x -fPIC -pedantic -g -Wno-missing-field-initializers -Wno-switch -Wno-multichar   -ftree-vectorize  -ftree-vectorize -mssse3  backend.h uvc-v4l2.cpp wrap.cpp  -o wrap.so
  backend.h:4:9: warning: #pragma once in main file
   #pragma once
           ^
  In file included from /usr/local/include/pybind11/pytypes.h:12:0,
                   from /usr/local/include/pybind11/cast.h:13,
                   from /usr/local/include/pybind11/attr.h:13,
                   from /usr/local/include/pybind11/pybind11.h:36,
                   from wrap.cpp:1:
  /usr/local/include/pybind11/common.h:72:20: fatal error: Python.h: No such file or directory
   #include &lt;Python.h&gt;
                      ^
  compilation terminated.
  </code></pre>
  
  <p>However, I do seem to have the file: </p>
  
  <pre><code>$ find /usr -name Python.h
  /usr/include/python2.7/Python.h
  /usr/include/python3.5m/Python.h
  </code></pre>
  
  <p><strong>Which (path?) should I correct so <code>g++</code> would be able to locate <code>Python.h</code>?</strong></p>
  
  <p><br><p>Notes:</p>
  
  <pre><code>$ apt list | grep -iE -- '^python.-dev|^python-dev'
  
  WARNING: apt does not have a stable CLI interface. Use with caution in scripts.
  
  python-dev/xenial,now 2.7.11-1 amd64 [installed]
  python3-dev/xenial,now 3.5.1-3 amd64 [installed]
  
  $ dpkg -S Python.h
  libpython2.7-dev:amd64: /usr/include/python2.7/Python.h
  libpython3.5-dev:amd64: /usr/include/python3.5m/Python.h
  
  $ dpkg -L python2.7-dev
  /.
  /usr
  /usr/bin
  /usr/share
  /usr/share/man
  /usr/share/man/man1
  /usr/share/doc
  /usr/share/doc/python2.7
  /usr/share/doc/python2.7/x86_64-linux-gnu
  /usr/share/doc/python2.7/x86_64-linux-gnu/test_results.gz
  /usr/share/doc/python2.7/x86_64-linux-gnu/pybench.log.gz
  /usr/share/doc/python2.7/gdbinit.gz
  /usr/share/doc/python2.7/HISTORY.gz
  /usr/share/doc/python2.7/README.valgrind.gz
  /usr/share/doc/python2.7/README.maintainers
  /usr/bin/python2.7-config
  /usr/share/man/man1/python2.7-config.1.gz
  /usr/share/doc/python2.7-dev
  </code></pre>