title: How to get QGIS debug output
body: <p>I am trying to get my build of QGIS to output the debug messages from calls to QgsDebugMsg. Here's what I have so far:</p>
  
  <p>I've built QGIS configured as RelWithDebugInfo and in the application's <code>Help &gt; About &gt; About</code> window, I see the text: "This copy of QGIS writes debugging output."</p>
  
  <p>In the application's <code>Options &gt; System &gt; Environment Variables</code> window, I've set the environment variables: <code>QGIS_DEBUG = 9</code> and <code>QGIS_LOG_FILE = C:\Users\USER\Documents\QGIS\log.txt</code></p>
  
  <p>However, the log file isn't getting created at all. What am I missing?</p>