# Running Mutter

## Environment Variables

Mutter automatically checks environment variables during its initialization. These environment variables are meant as debug tools or overrides for default behaviours:

MUTTER_VERBOSE

  Enable verbose mode, in which more information is printed to the console. Mutter needs to be built with the --enable-verbose-mode option (enabled by default). For more fine-grained control of the output, see meta_add_verbose_topic().

MUTTER_DEBUG

  Traps and prints X errors to the console.

MUTTER_G_FATAL_WARNINGS

  Causes any logging from the domains Mutter, Gtk, Gdk, Pango or GLib to terminate the process (only when using the log functions in GLib).

MUTTER_USE_LOGFILE

  Log all messages to a temporary file.

MUTTER_DEBUG_XINERAMA

  Log extra information about support of the XINERAMA extension.

MUTTER_DEBUG_SM

  Log extra information about session management.

MUTTER_DEBUG_BUTTON_GRABS

  Log extra information about button grabs.

MUTTER_SYNC

  Call XSync after each X call.

MUTTER_DISPLAY

  Name of the X11 display to use.

META_DISABLE_MIPMAPS

  Disable use of mipmaps for the textures that back window pixmaps.

MUTTER_USE_STATIC_GRAVITY

  Enable support for clients with static bit-gravity.

MUTTER_WM_CLASS_FILTER

  Comma-separated list of WM_CLASS names to which to restrict Mutter to.

MUTTER_DISABLE_FALLBACK_COLOR

  Disable fallback for themed colors, for easier detection of typographical errors.