title: How to properly set installed-size for deb package?
body: <p>I'm developing debian packages and I have troubles with correctly defining 'Installed-Size' under DEBIAN/control.<br>
  I have created a script that continuously checks svn repository for new revisions, and if found some changes then calculates code's size (excluding DEBIAN folder) with <strong>du -s</strong> command and then this value is placed to 'Installed-size'. </p>
  
  <p>DEBIAN/control file looks like follows:</p>
  
  <pre><code>Package: myfirstdebpackage
  Version: 1.0
  Architecture: all
  Maintainer: me
  Installed-Size: 16664
  Depends: python (&gt;=2.7), python-appindicator, python-numpy, python-suds
  Section: extras
  Priority: optional
  Homepage: www.example.com
  Description: My first deb package
  </code></pre>
  
  <p>Application's folder structure:</p>
  
  <pre><code>myfirstdebpackage/DEBIAN
  myfirstdebpackage/usr/bin/myfirstdebpackage/&lt;files&gt;
  </code></pre>
  
  <p>First installation goes well (via apt repository) but after creating a newer version and trying to update package I got 'size-mismatch' or 'Hash Sum mismatch' error. </p>
  
  <p>What's wrong?</p>