# Part II. Running Muffin

## Environment Variables

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

MUFFIN_VERBOSE | Enable verbose mode, in which more information is printed to the console. Muffin 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()`.
MUFFIN_DEBUG | Traps and prints X errors to the console.
MUFFIN_G_FATAL_WARNINGS | Causes any logging from the domains Muffin, Gtk, Gdk, Pango or GLib to terminate the process (only when using the log functions in GLib).
MUFFIN_USE_LOGFILE | Log all messages to a temporary file.
MUFFIN_DEBUG_XINERAMA | Log extra information about support of the XINERAMA extension.
MUFFIN_DEBUG_SM | Log extra information about session management.
MUFFIN_DEBUG_BUTTON_GRABS | Log extra information about button grabs.
MUFFIN_SYNC | Call XSync after each X call.
MUFFIN_DISPLAY | Name of the X11 display to use.
META_DISABLE_MIPMAPS | Disable use of mipmaps for the textures that back window pixmaps.
MUFFIN_USE_STATIC_GRAVITY | Enable support for clients with static bit-gravity.
MUFFIN_WM_CLASS_FILTER | Comma-separated list of WM_CLASS names to which to restrict Muffin to.
MUFFIN_DISABLE_FALLBACK_COLOR | Disable fallback for themed colors, for easier detection of typographical errors.