ApplicationCommandLine
GApplicationCommandLine
represents a command-line invocation of an application.
It is created by class@Gio.Application and emitted in the signal@Gio.Application::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 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::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::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.
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.
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::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.
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
return G_SOURCE_REMOVE;
}
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::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
Skipped during bindings generation
parameter
argc
: argc: Out parameter is not supportedmethod
print
: Varargs parameter is not supportedmethod
printerr
: Varargs parameter is not supportedmethod
arguments
: Property has no getter nor settermethod
options
: Property has no getter nor settermethod
platform-data
: Property has no getter nor setter
Constructors
Functions
Creates a #GFile corresponding to a filename that was given as part of the invocation of @cmdline.
Gets the contents of the 'environ' variable of the command line invocation, as would be returned by g_get_environ(), ie as a null-terminated list of strings in the form 'NAME=VALUE'. The strings may contain non-utf8 data.
Gets the exit status of @cmdline. See g_application_command_line_set_exit_status() for more information.
Gets the options that were passed to g_application_command_line().
Gets the platform data associated with the invocation of @cmdline.
Gets the stdin of the invoking process.
Prints a message using the stderr print handler in the invoking process.
Prints a message using the stdout print handler in the invoking process.
Sets the exit status that will be used when the invoking process exits.