Common commandline options

All GTK+ applications support a number of standard commandline options. These are removed from argv by gtk_init(). Modules may parse and remove further options. The X11 and Windows GDK backends parse some additional commandline options.

--gtk-module module.  A list of modules to load in addition to those specified in the GTK_MODULES environment variable and the gtk-modules setting.

--g-fatal-warnings.  Make GTK+ abort on all warnings. This is useful to stop on the first warning in a debugger, if your application is printing multiple warnings. It's almost always best to start debugging with the first warning that occurs.

--gtk-debug options.  A list of debug options to turn on in addition to those specified in the GTK_DEBUG environment variable. This option is only available if GTK+ has been configured with --enable-debug=yes.

--gtk-no-debug options.  A list of debug options to turn off. This option is only available if GTK+ has been configured with --enable-debug=yes.

The following options are really used by GDK, not by GTK+, but we list them here for completeness nevertheless.

--class class.  Sets the program class; see gdk_set_program_class().

--name name.  Sets the program name.

--gdk-debug options.  A list of debug options to turn on in addition to those specified in the GDK_DEBUG environment variable. This option is only available if GTK+ has been configured with --enable-debug=yes.

--gdk-no-debug options.  A list of debug options to turn off. This option is only available if GTK+ has been configured with --enable-debug=yes.

Environment variables

GTK+ inspects a number of environment variables in addition to standard variables like LANG, PATH, HOME or DISPLAY; mostly to determine paths to look for certain files. The X11, Windows and Framebuffer GDK backends use some additional environment variables.

GTK_DEBUG.  If GTK+ has been configured with --enable-debug=yes, this variable can be set to a list of debug options, which cause GTK+ to print out different types of debugging information.

The special value all can be used to turn on all debug options.

GTK_MODULES.  A list of modules to load.

GTK_PATH.  Specifies a list of directories to search when GTK+ is looking for dynamically loaded objects such as the modules specified by GTK_MODULES, theme engines, input method modules, file system backends and print backends. If the path to the dynamically loaded object is given as an absolute path name, then GTK+ loads it directly. Otherwise, GTK+ goes in turn through the directories in GTK_PATH, followed by the directory .gtk-2.0 in the user's home directory, followed by the system default directory, which is libdir/gtk-2.0/modules. (If GTK_EXE_PREFIX is defined, libdir is $GTK_EXE_PREFIX/lib. Otherwise it is the libdir specified when GTK+ was configured, usually /usr/lib, or /usr/local/lib.) For each directory in this list, GTK+ actually looks in a subdirectory directory/version/host/type Where version is derived from the version of GTK+ (use pkg-config --variable=gtk_binary_version gtk+-2.0 to determine this from a script), host is the architecture on which GTK+ was built. (use pkg-config --variable=gtk_host gtk+-2.0 to determine this from a script), and type is a directory specific to the type of modules; currently it can be modules, engines, immodules, filesystems or printbackends, corresponding to the types of modules mentioned above. Either version, host, or both may be omitted. GTK+ looks first in the most specific directory, then in directories with fewer components. The components of GTK_PATH are separated by the ':' character on Linux and Unix, and the ';' character on Windows.

GTK_IM_MODULE.  Specifies an IM module to use in preference to the one determined from the locale.

GTK_IM_MODULE_FILE.  Specifies the file listing the IM modules to load. This environment variable overrides the im_module_file specified in the RC files, which in turn overrides the default value sysconfdir/gtk-2.0/gtk.immodules (sysconfdir is the sysconfdir specified when GTK+ was configured, usually /usr/local/etc.)

GTK2_RC_FILES.  Specifies a list of RC files to parse instead of the default ones; see Resource Files.

GTK_EXE_PREFIX.  If set, GTK+ uses $GTK_EXE_PREFIX/lib instead of the libdir configured when GTK+ was compiled.

GTK_DATA_PREFIX.  If set, makes GTK+ use $GTK_DATA_PREFIX instead of the prefix configured when GTK+ was compiled.

The following environment variables are used by GdkPixbuf, GDK or Pango, not by GTK+ itself, but we list them here for completeness nevertheless.

GDK_PIXBUF_MODULE_FILE.  Specifies the file listing the GdkPixbuf loader modules to load. This environment variable overrides the default value sysconfdir/gtk-2.0/gdk-pixbuf.loaders (sysconfdir is the sysconfdir specified when GTK+ was configured, usually /usr/local/etc.)

GDK_DEBUG.  If GTK+ has been configured with --enable-debug=yes, this variable can be set to a list of debug options, which cause GDK to print out different types of debugging information.

The special value all can be used to turn on all debug options.

XDG_DATA_HOME, XDG_DATA_DIRS.  GTK+ uses these environment variables to locate icon themes and MIME information. For more information, see Icon Theme Specification, the Shared MIME-info Database and the Base Directory Specification.