Object Hierarchy:

GLib.ApplicationCommandLine GLib.ApplicationCommandLine GLib.ApplicationCommandLine GLib.Object GLib.Object GLib.Object->GLib.ApplicationCommandLine


[ CCode ( type_id = "g_application_command_line_get_type ()" ) ]
public class ApplicationCommandLine : Object

`GApplicationCommandLine` represents a command-line invocation of an application.

It is created by [class@Gio.Application] and emitted in the [signal@Gio.Application:GApplicationCommandLine:command-line] signal and virtual function.

The class contains the list of arguments that the program was invoked with. It is also possible to query if the commandline invocation was local (ie: the current process is running in direct response to the invocation) or remote (ie: some other process forwarded the commandline to this process).

The `GApplicationCommandLine` object can provide the argc and argv parameters for use with the [ struct@GLib.OptionContext] command-line parsing API, with the [method@Gio.ApplicationCommandLine.get_arguments] function. See gapplication-example-cmdline3.c for an example.

The exit status of the originally-invoked process may be set and messages can be printed to stdout or stderr of that process.

For remote invocation, the originally-invoked process exits when [method@Gio.ApplicationCommandLine.done] method is called. This method is also automatically called when the object is disposed.

The main use for `GApplicationCommandLine` (and the [signal@Gio.Application:GApplicationCommandLine:command-line] signal) is 'Emacs server' like use cases: You can set the `EDITOR` environment variable to have e.g. git use your favourite editor to edit commit messages, and if you already have an instance of the editor running, the editing will happen in the running instance, instead of opening a new one. An important aspect of this use case is that the process that gets started by git does not return until the editing is done.

Normally, the commandline is completely handled in the [signal@Gio.Application:GApplicationCommandLine:command-line] handler. The launching instance exits once the signal handler in the primary instance has returned, and the return value of the signal handler becomes the exit status of the launching instance.

```c static int command_line (GApplication *application, GApplicationCommandLine *cmdline) { gchar **argv; gint argc; gint i;

argv = g_application_command_line_get_arguments (cmdline, &argc);

g_application_command_line_print (cmdline, "This text is written back\n" "to stdout of the caller\n");

for (i = 0; i < argc; i++) g_print ("argument d: s\n", i, argv[i]);

g_strfreev (argv);

return 0; } ```

The complete example can be found here: gapplication-example-cmdline.c

In more complicated cases, the handling of the commandline can be split between the launcher and the primary instance.

```c static gboolean test_local_cmdline (GApplication *application, gchar ***arguments, gint *exit_status) { gint i, j; gchar **argv;

argv = *arguments;

if (argv[0] == NULL) { *exit_status = 0; return FALSE; }

i = 1; while (argv[i]) { if (g_str_has_prefix (argv[i], "--local-")) { g_print ("handling argument s locally\n", argv[i]); g_free (argv[i]); for (j = i; argv[j]; j++) argv[j] = argv[j + 1]; } else { g_print ("not handling argument s locally\n", argv[i]); i++; } }

*exit_status = 0;

return FALSE; }

static void test_application_class_init (TestApplicationClass *class) { G_APPLICATION_CLASS (class)->local_command_line = test_local_cmdline;

... } ```

In this example of split commandline handling, options that start with `--local-` are handled locally, all other options are passed to the [ signal@Gio.Application:GApplicationCommandLine:command-line] handler which runs in the primary instance.

The complete example can be found here: gapplication-example-cmdline2.c

If handling the commandline requires a lot of work, it may be better to defer it.

```c static gboolean my_cmdline_handler (gpointer data) { GApplicationCommandLine *cmdline = data;

// do the heavy lifting in an idle

g_application_command_line_set_exit_status (cmdline, 0); g_object_unref (cmdline); // this releases the application


static int command_line (GApplication *application, GApplicationCommandLine *cmdline) { // keep the application running until we are done with this commandline g_application_hold (application);

g_object_set_data_full (G_OBJECT (cmdline), "application", application, (GDestroyNotify)g_application_release);

g_object_ref (cmdline); g_idle_add (my_cmdline_handler, cmdline);

return 0; } ```

In this example the commandline is not completely handled before the [signal@Gio.Application:GApplicationCommandLine:command-line] handler returns. Instead, we keep a reference to the `GApplicationCommandLine` object and handle it later (in this example, in an idle). Note that it is necessary to hold the application until you are done with the commandline.

The complete example can be found here: gapplication-example-cmdline3.c

Example: Commandline-handling and GLib.Applications:

public class MyApplication : Application {
private int counter = 0;

private MyApplication () {
Object (application_id: "org.example.application", flags: ApplicationFlags.HANDLES_COMMAND_LINE);
set_inactivity_timeout (10000);

public override void activate () {
this.hold ();
print ("Activated\n");
this.release ();

private int _command_line (ApplicationCommandLine command_line) {
bool version = false;
bool count = false;

OptionEntry[] options = new OptionEntry[2];
options[0] = { "version", 0, 0, OptionArg.NONE, ref version, "Display version number", null };
options[1] = { "count", 0, 0, OptionArg.NONE, ref count, "Display version number", null };

// We have to make an extra copy of the array, since .parse assumes
// that it can remove strings from the array without freeing them.
string[] args = command_line.get_arguments ();
string*[] _args = new string[args.length];
for (int i = 0; i < args.length; i++) {
_args[i] = args[i];

try {
var opt_context = new OptionContext ("- OptionContext example");
opt_context.set_help_enabled (true);
opt_context.add_main_entries (options, null);
unowned string[] tmp = _args;
opt_context.parse (ref tmp);
} catch (OptionError e) {
command_line.print ("error: %s\n", e.message);
command_line.print ("Run '%s --help' to see a full list of available command line options.\n", args[0]);
return 0;

if (version) {
command_line.print ("Test 0.1\n");
return 0;

if (count) {
command_line.print ("%d\n", ++this.counter);
return 0;

return 0;

public override int command_line (ApplicationCommandLine command_line) {
// keep the application running until we are done with this commandline
this.hold ();
int res = _command_line (command_line);
this.release ();
return res;

public static int main (string[] args) {
MyApplication app = new MyApplication ();
int status = (args);
return status;

valac --pkg gio-2.0 GLib.Application.4.vala

Namespace: GLib
Package: gio-2.0



Creation methods:


Inherited Members: