Logging

Sometimes the problem is so obvious that you will simply get the error directly from the command line or in the server log file.

Basics

Otherwise, a good first step is to start xpra from the command line and add "-d CATEGORY" to it, for example to debug geometry issues:

xpra attach -d geometry

The full list of debugging categories can be found with xpra -d help, see wiki/Logging/Categories for a command output example.

Use the special category value "all" to enable all logging. (this will be very verbose)

You can also prefix the CATEGORY with a dash "-" to disable debug logging for it. For example, to log everything except "window" category:

xpra start :10 -d all,-window

Environment Variables

Each logging category can also be enabled using environment variable, which can be useful if you cannot modify the command line, or if the logging should happen very early on, or if you aren't calling the code from its normal wrappers. Use: XPRA_CATEGORY_DEBUG=1 xpra ... to enable debug logging for your chosen CATEGORY.

Xpra control interface

It is also possible to enable and disable debug logging of a server at runtime using:

xpra control :DISPLAY debug enable CATEGORY

and

xpra control :DISPLAY debug enable CATEGORY

And you can get the current list of debug loggers which:

xpra control :DISPLAY debug status

These commands are also available trough the server's dbus interface, see #904.

Detailed Logging

Some subsystems require special environment variables to enable logging, this is to minimize the cost of logging in performance critical paths. In particular the X11 bindings which can process thousands of events per second.

For example:

• x11 event handling:

  XPRA_X11_DEBUG_EVENTS="*" xpra start :10
  

or

XPRA_X11_DEBUG_EVENTS="EnterNotify,CreateNotify" xpra start :10

• XShm and image debugging code:

  XPRA_XSHM_DEBUG=1 xpra start :10
  

or

XPRA_XIMAGE_DEBUG=1 xpra start :10

Please refer to the source code for details and more up to date information.