GIO inspects a few of environment variables in addition to the ones used by GLib.

XDG_DATA_HOME, XDG_DATA_DIRS.  GIO uses these environment variables to locate MIME information. For more information, see the Shared MIME-info Database and the Base Directory Specification.

GVFS_DISABLE_FUSE.  This variable can be set to keep Gvfs from starting the fuse backend, which may be unwanted or unnecessary in certain situations.

The following environment variables are only useful for debugging GIO itself or modules that it loads. They should not be set in a production environment.

GIO_USE_VFS.  This environment variable can be set to the name of a GVfs implementation to override the default for debugging purposes. The GVfs implementation for local files that is included in GIO has the name "local", the implementation in the gvfs module has the name "gvfs".

GIO_USE_VOLUME_MONITOR.  This variable can be set to the name of a GVolumeMonitor implementation to override the default for debugging purposes. The GVolumeMonitor implementation for local files that is included in GIO has the name "unix", the hal-based implementation in the gvfs module has the name "hal".

GIO_USE_URI_ASSOCIATION.  This variable can be set to the name of a GDesktopAppInfoLookup implementation to override the default for debugging purposes. GIO does not include a GDesktopAppInfoLookup implementation, the GConf-based implementation in the gvfs module has the name "gconf".

GVFS_INOTIFY_DIAG.  When this environment variable is set and GIO has been built with inotify support, a dump of diagnostic inotify information will be written every 20 seconds to a file named /tmp/gvfsdid.pid.

GIO_EXTRA_MODULES.  When this environment variable is set to a path, or a set of paths separated by a colon, GIO will attempt to load modules from within the path.