Using log files

Log files provide a way of tracking exactly what is going on in a Python plugin or script by creating messages that are available even if the script or QGIS crashes. These log messages make troubleshooting easier. In this recipe, we'll demonstrate two methods used for logging. One method is the actual log files on the filesystem, and the other is the QGIS Log Messages Panel window, which is available by clicking on the yellow triangle with an exclamation mark at the bottom-right corner of the QGIS application window, or by selecting the View menu, then clicking on Panels, and then checking Log Messages Panel.

Getting ready

To use log files, we must configure the QGIS_LOG_FILE environment variable by performing the following steps so that QGIS knows where to write log messages:

1. From the QGIS Settings menu, select Options....
2. In the Options dialog, select System panel.
3. In the System panel, scroll down to the Environment section.
4. In the Environment section, check the Use...