## Running GTK+ Applications

Running GTK+ Applications — How to run and debug your GTK+ application

## Running and debugging GTK+ Applications

### 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.

misc | Miscellaneous information
plugsocket | Cross-process embedding
text | Text widget internals
tree | Tree widget internals
updates | Visual feedback about window updates
keybindings | Keybindings
multihead | Working on multiple displays
modules | Loading of modules
geometry | Size allocation
icontheme | Icon themes
printing | Printing support

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

`GTK_MODULES`. A list of modules to load. Note that GTK+ also allows to specify modules to load via a commandline option (`--gtk-module`) and with the `gtk-modules` setting.

`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. If this isn't set and you are running on the system that enables `XSETTINGS` and has a value in `Gtk/IMModule`, that will be used for the default IM module.

`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.

misc | Miscellaneous information
events | Show all events received by GDK
dnd | Information about drag-and-drop
xim | Information about XIM support

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

`GDK_NATIVE_WINDOWS`. If set, GDK creates all windows as native windows. This can help applications that make assumptions about 1-1 correspondence between GDK windows and X11 windows.

`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.