title: Installing python module IOError: [Errno 13] Permission denied:
body: <p>I tried to install the python library openpyxl using pip by typing into the terminal:</p>
  
  <pre><code>    pip install openpyxl
  </code></pre>
  
  <p>But it was not executed properly. It threw an exception:</p>
  
  <pre><code>    Successfully built openpyxl jdcal et-xmlfile
      Installing collected packages: jdcal, et-xmlfile, openpyxl
      Exception:
      Traceback (most recent call last):
      File "/Library/Python/2.7/site-packages/pip/basecommand.py", line 215, in main
      status = self.run(options, args)
      File "/Library/Python/2.7/site-packages/pip/commands/install.py", line 342, in run
      prefix=options.prefix_path,
      File "/Library/Python/2.7/site-packages/pip/req/req_set.py", line 784, in install
      **kwargs
      File "/Library/Python/2.7/site-packages/pip/req/req_install.py", line 851, in install
      self.move_wheel_files(self.source_dir, root=root, prefix=prefix)
      File "/Library/Python/2.7/site-packages/pip/req/req_install.py", line 1064, in move_wheel_files
      isolated=self.isolated,
      File "/Library/Python/2.7/site-packages/pip/wheel.py", line 345, in move_wheel_files
      clobber(source, lib_dir, True)
      File "/Library/Python/2.7/site-packages/pip/wheel.py", line 323, in clobber
      shutil.copyfile(srcfile, destfile)
      File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/shutil.py", line 83, in copyfile
      with open(dst, 'wb') as fdst:
      IOError: [Errno 13] Permission denied: '/Library/Python/2.7/site-packages/jdcal.py'
  </code></pre>