class Gio::ApplicationCommandLine

• Gio::ApplicationCommandLine
• GObject::Object
• Reference
• Object

Overview

GApplicationCommandLine represents a command-line invocation of an application.

It is created by 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 GLib::OptionContext command-line parsing API, with the Gio::ApplicationCommandLine#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 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.

WARNING ⚠️ The following code is in 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.

WARNING ⚠️ The following code is in 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::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.

WARNING ⚠️ The following code is in 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

  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

Defined in:

Constructors

• .new

  Initialize a new ApplicationCommandLine.

• .new(*, arguments : GLib::Variant | Nil = nil, is_remote : Bool | Nil = nil, options : GLib::Variant | Nil = nil, platform_data : GLib::Variant | Nil = nil)

Class Method Summary

• .g_type : UInt64

  Returns the type id (GType) registered in GLib type system.

Instance Method Summary

• #==(other : self)

  Returns true if this reference is the same as other.

• #arguments : Enumerable(String)

  Gets the list of arguments that was passed on the command line.

• #arguments=(value : GLib::Variant | Nil) : GLib::Variant | Nil
• #create_file_for_arg(arg : String) : Gio::File

  Creates a #GFile corresponding to a filename that was given as part of the invocation of cmdline.

• #cwd : Path | Nil

  Gets the working directory of the command line invocation.

• #done : Nil

  Signals that command line processing is completed.

• #environ : Enumerable(String)

  Gets the contents of the 'environ' variable of the command line invocation, as would be returned by g_get_environ(), ie as a nil-terminated list of strings in the form 'NAME=VALUE'.

• #exit_status : Int32

  Gets the exit status of cmdline.

• #exit_status=(exit_status : Int32) : Nil

  Sets the exit status that will be used when the invoking process exits.

• #getenv(name : String) : String | Nil

  Gets the value of a particular environment variable of the command line invocation, as would be returned by g_getenv().

• #hash(hasher)

  See Object#hash(hasher)

• #is_remote : Bool

  Determines if cmdline represents a remote invocation.

• #is_remote? : Bool
• #options=(value : GLib::Variant | Nil) : GLib::Variant | Nil
• #options_dict : GLib::VariantDict

  Gets the options that were passed to g_application_command_line().

• #platform_data : GLib::Variant | Nil

  Gets the platform data associated with the invocation of cmdline.

• #platform_data=(value : GLib::Variant | Nil) : GLib::Variant | Nil
• #print_literal(message : String) : Nil

  Prints a message using the stdout print handler in the invoking process.

• #printerr_literal(message : String) : Nil

  Prints a message using the stderr print handler in the invoking process.

• #stdin : Gio::InputStream | Nil

  Gets the stdin of the invoking process.

Constructor Detail

Class Method Detail

Instance Method Detail