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<refentry id="gtk-running">
<refmeta>
<refentrytitle>Running GTK+ Applications</refentrytitle>
<manvolnum>3</manvolnum>
<refmiscinfo>GTK Library</refmiscinfo>
</refmeta>

<refnamediv>
<refname>Running GTK+ Applications</refname>
<refpurpose>
How to run and debug your GTK+ application
</refpurpose>
</refnamediv>

<refsect1>
<title>Running and debugging GTK+ Applications</title>

<refsect2>
<title>Common commandline options</title>

<para>
All GTK+ applications support a number of standard commandline
options. These are removed from <literal>argv</literal> by gtk_init().
Modules may parse and remove further options. The
<link linkend="x11-cmdline">X11</link> and
<link linkend="win32-cmdline">Windows</link> GDK backends parse
some additional commandline options.
</para>

<formalpara>
<title><systemitem>--gtk-module <replaceable>module</replaceable></systemitem></title>

<para>
A list of modules to load in addition to those specified in the
<envar>GTK_MODULES</envar> environment variable and the
<literal>gtk-modules</literal> setting.
</para>
</formalpara>

<formalpara>
<title><systemitem>--g-fatal-warnings</systemitem></title>

<para>
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.
</para>
</formalpara>

<formalpara>
<title><systemitem>--gtk-debug <replaceable>options</replaceable></systemitem></title>

<para>
A list of <link linkend="GTK-Debug-Options">debug options</link>
to turn on in addition to those specified in the <envar>GTK_DEBUG</envar>
environment variable. This option is only available if GTK+ has been
configured with <option>--enable-debug=yes</option>.
</para>
</formalpara>

<formalpara>
<title><systemitem>--gtk-no-debug <replaceable>options</replaceable></systemitem></title>

<para>
A list of <link linkend="GTK-Debug-Options">debug options</link>
to turn off. This option is only available if GTK+ has been configured with
<option>--enable-debug=yes</option>.
</para>
</formalpara>

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

<formalpara>
<title><systemitem>--class <replaceable>class</replaceable></systemitem></title>

<para>
Sets the program class; see gdk_set_program_class().
</para>
</formalpara>

<formalpara>
<title><systemitem>--name <replaceable>name</replaceable></systemitem></title>

<para>
Sets the program name.
</para>
</formalpara>

<formalpara>
<title><systemitem>--gdk-debug <replaceable>options</replaceable></systemitem></title>

<para>
A list of <link linkend="GDK-Debug-Options">debug options</link>
to turn on in addition to those specified in the <envar>GDK_DEBUG</envar>
environment variable. This option is only available if GTK+ has been
configured with <option>--enable-debug=yes</option>.
</para>
</formalpara>

<formalpara>
<title><systemitem>--gdk-no-debug <replaceable>options</replaceable></systemitem></title>

<para>
A list of <link linkend="GDK-Debug-Options">debug options</link>
to turn off. This option is only available if GTK+ has been configured with
<option>--enable-debug=yes</option>.
</para>
</formalpara>

</refsect2>

<refsect2>
<title>Environment variables</title>

<para>
GTK+ inspects a number of environment variables in addition to standard
variables like <envar>LANG</envar>, <envar>PATH</envar>, <envar>HOME</envar>
or <envar>DISPLAY</envar>; mostly to determine paths to look for certain
files. The <link linkend="x11-envar">X11</link>,
<link linkend="win32-envar">Windows</link> and
<link linkend="fb-envar">Framebuffer</link> GDK backends use some
additional environment variables.
</para>

<formalpara id="GTK-Debug-Options">
  <title><envar>GTK_DEBUG</envar></title>

  <para>
  If GTK+ has been configured with <option>--enable-debug=yes</option>,
  this variable can be set to a list of debug options, which cause GTK+
  to print out different types of debugging information.
  <variablelist>
    <varlistentry>
      <term>misc</term>
      <listitem><para>Miscellaneous information</para></listitem>
    </varlistentry>
    <varlistentry>
      <term>plugsocket</term>
      <listitem><para>Cross-process embedding</para></listitem>
    </varlistentry>
    <varlistentry>
      <term>text</term>
      <listitem><para>Text widget internals</para></listitem>
    </varlistentry>
    <varlistentry>
      <term>tree</term>
      <listitem><para>Tree widget internals</para></listitem>
    </varlistentry>
    <varlistentry>
      <term>updates</term>
      <listitem><para>Visual feedback about window updates</para></listitem>
    </varlistentry>
    <varlistentry>
      <term>keybindings</term>
      <listitem><para>Keybindings</para></listitem>
    </varlistentry>
    <varlistentry>
      <term>multihead</term>
      <listitem><para>Working on multiple displays</para></listitem>
    </varlistentry>
    <varlistentry>
      <term>modules</term>
      <listitem><para>Loading of modules</para></listitem>
    </varlistentry>
    <varlistentry>
      <term>geometry</term>
      <listitem><para>Size allocation</para></listitem>
    </varlistentry>
    <varlistentry>
      <term>icontheme</term>
      <listitem><para>Icon themes</para></listitem>
    </varlistentry>
    <varlistentry>
      <term>printing</term>
      <listitem><para>Printing support</para></listitem>
    </varlistentry>
    <varlistentry>
      <term>builder</term>
      <listitem><para>GtkBuilder support</para></listitem>
    </varlistentry>

  </variablelist>
  The special value <literal>all</literal> can be used to turn on all
  debug options.
  </para>
</formalpara>

<formalpara>
  <title><envar>GTK_MODULES</envar></title>

  <para>
    A list of modules to load. Note that GTK+ also allows to specify modules to load via a commandline option (<option>--gtk-module</option>) and with the <literal>gtk-modules</literal> setting.
  </para>
  <warning>
    Note that this environment variable is read by GTK+ 2.x too,
    which may not have the same set of modules available for loading.
  </warning>
</formalpara>

<formalpara id="gtk-path">
  <title><envar>GTK_PATH</envar></title>

  <para>
    Specifies a list of directories to search when GTK+ is looking for
    dynamically loaded objects such as the modules specified by
    <envar>GTK_MODULES</envar>, 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 <envar>GTK_PATH</envar>,
    followed by the directory <filename>.gtk-3.0</filename> in the user's
    home directory, followed by the system default directory,
    which is <filename><replaceable>libdir</replaceable>/gtk-3.0/modules</filename>.
    (If <envar>GTK_EXE_PREFIX</envar> is defined, <replaceable>libdir</replaceable> is
    <filename>$GTK_EXE_PREFIX/lib</filename>. Otherwise it is the libdir
    specified when GTK+ was configured, usually
    <filename>/usr/lib</filename>, or
    <filename>/usr/local/lib</filename>.)
    For each directory in this list, GTK+ actually looks in a
    subdirectory
    <filename><replaceable>directory</replaceable>/<replaceable>version</replaceable>/<replaceable>host</replaceable>/<replaceable>type</replaceable></filename>
    Where <replaceable>version</replaceable> is derived from the
    version of GTK+ (use <literal>pkg-config
    --variable=gtk_binary_version gtk+-3.0</literal> to determine this from a
    script), <replaceable>host</replaceable> is the architecture on
    which GTK+ was built. (use <literal>pkg-config
    --variable=gtk_host gtk+-3.0</literal> to determine this from a
    script), and <replaceable>type</replaceable> is a directory
    specific to the type of modules; currently it can be
    <literal>modules</literal>, <literal>engines</literal>,
    <literal>immodules</literal>, <literal>filesystems</literal> or
    <literal>printbackends</literal>, corresponding to the types of
    modules mentioned above. Either <replaceable>version</replaceable>,
    <replaceable>host</replaceable>, 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.
  </para>
  <warning>
    Note that this environment variable is read by GTK+ 2.x too, which
    makes it unsuitable for setting it system-wide (or session-wide),
    since doing so will cause either GTK+ 2.x applications or GTK+ 3
    applications to see incompatible modules.
  </warning>
</formalpara>

<formalpara>
  <title><envar>GTK_IM_MODULE</envar></title>

  <para>
    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 <literal>XSETTINGS</literal> and has a value in
    <literal>Gtk/IMModule</literal>, that will be used for the default
    IM module.
  </para>
</formalpara>

<formalpara id="gtk-im-module-file">
  <title><envar>GTK_IM_MODULE_FILE</envar></title>

  <para>
    Specifies the file listing the IM modules to load. This environment
    variable the default value
    <filename><replaceable>libdir</replaceable>/gtk-3.0/3.0.0/immodules.cache</filename>
    (<replaceable>libdir</replaceable> has the same meaning here as explained for <envar>GTK_PATH</envar>).
  </para>
  <para>
    The <filename>immodules.cache</filename> file is generated by the
    <command>gtk-query-immodules-3.0</command> utility.
  </para>
  <warning>
    Note that this environment variable is read by GTK+ 2.x too, which
    makes it unsuitable for setting it system-wide (or session-wide),
    since doing so will cause either GTK+ 2.x applications or GTK+ 3
    applications to see the wrong list of IM modules.
  </warning>
</formalpara>

<formalpara>
  <title><envar>GTK_EXE_PREFIX</envar></title>

  <para>
    If set, GTK+ uses <filename>$GTK_EXE_PREFIX/lib</filename> instead of
    the libdir configured when GTK+ was compiled.
  </para>
</formalpara>

<formalpara>
  <title><envar>GTK_DATA_PREFIX</envar></title>

  <para>
    If set, makes GTK+ use <filename>$GTK_DATA_PREFIX</filename>
    instead of the prefix configured when GTK+ was compiled.
  </para>
</formalpara>

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

<formalpara>
  <title><envar>GDK_PIXBUF_MODULE_FILE</envar></title>

  <para>
    Specifies the file listing the GdkPixbuf loader modules to load.
    This environment variable overrides the default value
    <filename><replaceable>libdir</replaceable>/gtk-3.0/3.0.0/loaders.cache</filename>
    (<replaceable>libdir</replaceable> is the sysconfdir specified when
    GTK+ was configured, usually <filename>/usr/local/lib</filename>.)
  </para>
  <para>
    The <filename>loaders.cache</filename> file is generated by the
    <command>gdk-pixbuf-query-loaders</command> utility.
  </para>
 </formalpara>

<formalpara id="GDK-Debug-Options">
  <title><envar>GDK_DEBUG</envar></title>

  <para>
  If GTK+ has been configured with <option>--enable-debug=yes</option>,
  this variable can be set to a list of debug options, which cause GDK
  to print out different types of debugging information.
  <variablelist>
    <varlistentry>
      <term>misc</term>
      <listitem><para>Miscellaneous information</para></listitem>
    </varlistentry>
    <varlistentry>
      <term>events</term>
      <listitem><para>Show all events received by GDK</para></listitem>
    </varlistentry>
    <varlistentry>
      <term>dnd</term>
      <listitem><para>Information about drag-and-drop</para></listitem>
    </varlistentry>
    <varlistentry>
      <term>xim</term>
      <listitem><para>Information about XIM support</para></listitem>
    </varlistentry>
    <varlistentry>
      <term>nograbs</term>
      <listitem><para>Turn off all pointer and keyboard grabs</para></listitem>
    </varlistentry>
    <varlistentry>
      <term>multihead</term>
      <listitem><para>Information related to multiple screens</para></listitem>
    </varlistentry>
    <varlistentry>
      <term>xinerama</term>
      <listitem><para>Simulate a multi-monitor setup</para></listitem>
    </varlistentry>
    <varlistentry>
      <term>cursor</term>
      <listitem><para>Information about cursor objects (only win32)</para></listitem>
    </varlistentry>
    <varlistentry>
      <term>draw</term>
      <listitem><para>Information about drawing operations (only win32)</para></listitem>
    </varlistentry>
    <varlistentry>
      <term>eventloop</term>
      <listitem><para>Information about event loop operation (mostly Quartz)</para></listitem>
    </varlistentry>

  </variablelist>
  The special value <literal>all</literal> can be used to turn on all
  debug options.
  </para>
</formalpara>

<formalpara>
  <title><envar>GDK_BACKEND</envar></title>

  <para>
    If set, selects the GDK backend to use. Selecting a backend requires that GTK is compiled
    with support for that backend. The following backends can be selected:
    <variablelist>

      <varlistentry>
        <term>quartz</term>
        <listitem><para>Selects the native Quartz backend</para></listitem>
      </varlistentry>

      <varlistentry>
        <term>win32</term>
        <listitem><para>Selects the native backend for Microsoft Windows</para></listitem>
      </varlistentry>

      <varlistentry>
        <term>x11</term>
        <listitem><para>Selects the native backend for connecting to X11 servers.</para></listitem>
      </varlistentry>

    </variablelist>
    For more information about selecting backends, see the gdk_display_manager_get() function.
  </para>
</formalpara>

<formalpara>
  <title><envar>GDK_SYNCHRONIZE</envar></title>

  <para>
    If set, GDK makes all X requests synchronously. This is a useful
    option for debugging, but it will slow down the performance considerably.
  </para>
</formalpara>

<formalpara>
  <title><envar>XDG_DATA_HOME</envar>, <envar>XDG_DATA_DIRS</envar></title>

  <para>
    GTK+ uses these environment variables to locate icon themes
    and MIME information. For more information, see
    <ulink url="http://freedesktop.org/Standards/icon-theme-spec">Icon Theme Specification</ulink>,
    the <ulink url="http://freedesktop.org/Standards/shared-mime-info-spec">Shared MIME-info Database</ulink>
    and the <ulink url="http://freedesktop.org/Standards/basedir-spec">Base Directory Specification</ulink>.
  </para>
</formalpara>

<formalpara>
  <title><envar>DESKTOP_STARTUP_ID</envar></title>

  <para>
    GTK+ uses this environment variable to provide startup notification
    according to the <ulink url="http://standards.freedesktop.org/startup-notification-spec/startup-notification-latest.txt">Startup Notification Spec</ulink>.
    Following the specification, GTK+ unsets this variable after reading
    it (to keep it from leaking to child processes). So, if you need its
    value for your own purposes, you have to read it before calling
    gtk_init().
  </para>
</formalpara>

</refsect2>

</refsect1>

</refentry>
