GI.Gio.Objects.ApplicationCommandLine

ApplicationCommandLine represents a command-line invocation of an application. It is created by Application and emitted in the commandLine 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 OptionContext command-line parsing API, with the applicationCommandLineGetArguments function. See [gapplication-example-cmdline3.c][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. The lifecycle of the originally-invoked process is tied to the lifecycle of this object (ie: the process exits when the last reference is dropped).

The main use for ApplicationCommandLine (and the commandLine 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 commandLine 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 code

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 comandline can be split between the launcher and the primary instance.

C code

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

  argv = *arguments;

  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 commandLine 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 code

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 commandLine handler returns. Instead, we keep a reference to the ApplicationCommandLine 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

Exported types

newtype ApplicationCommandLine

Memory-managed wrapper type.

Constructors

ApplicationCommandLine (ManagedPtr ApplicationCommandLine)

Instances

Eq ApplicationCommandLine

Defined in GI.Gio.Objects.ApplicationCommandLine

Methods

(==) :: ApplicationCommandLine -> ApplicationCommandLine -> Bool

(/=) :: ApplicationCommandLine -> ApplicationCommandLine -> Bool

GObject ApplicationCommandLine

Defined in GI.Gio.Objects.ApplicationCommandLine

Methods

gobjectType :: IO GType

IsGValue ApplicationCommandLine

Convert ApplicationCommandLine to and from GValue with toGValue and fromGValue.

Defined in GI.Gio.Objects.ApplicationCommandLine

Methods

toGValue :: ApplicationCommandLine -> IO GValue

fromGValue :: GValue -> IO ApplicationCommandLine

HasParentTypes ApplicationCommandLine

Defined in GI.Gio.Objects.ApplicationCommandLine

type ParentTypes ApplicationCommandLine

Defined in GI.Gio.Objects.ApplicationCommandLine

type ParentTypes ApplicationCommandLine = '[Object]

class (GObject o, IsDescendantOf ApplicationCommandLine o) => IsApplicationCommandLine o

Type class for types which can be safely cast to ApplicationCommandLine, for instance with toApplicationCommandLine.

Instances

(GObject o, IsDescendantOf ApplicationCommandLine o) => IsApplicationCommandLine o

Defined in GI.Gio.Objects.ApplicationCommandLine

toApplicationCommandLine :: (MonadIO m, IsApplicationCommandLine o) => o -> m ApplicationCommandLine

Cast to ApplicationCommandLine, for types for which this is known to be safe. For general casts, use castTo.

noApplicationCommandLine :: Maybe ApplicationCommandLine

A convenience alias for Nothing :: Maybe ApplicationCommandLine.

Methods

Overloaded methods

createFileForArg

applicationCommandLineCreateFileForArg

Arguments

:: (HasCallStack, MonadIO m, IsApplicationCommandLine a)

=> a

cmdline: a ApplicationCommandLine

-> [Char]

arg: an argument from cmdline

-> m File

Returns: a new File

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

This differs from fileNewForCommandlineArg in that it resolves relative pathnames using the current working directory of the invoking process rather than the local process.

Since: 2.36

getArguments

applicationCommandLineGetArguments

Arguments

:: (HasCallStack, MonadIO m, IsApplicationCommandLine a)

=> a

cmdline: a ApplicationCommandLine

-> m [[Char]]

Returns: the string array containing the arguments (the argv)

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

The strings in the array may contain non-UTF-8 data on UNIX (such as filenames or arguments given in the system locale) but are always in UTF-8 on Windows.

If you wish to use the return value with OptionContext, you must use optionContextParseStrv.

The return value is Nothing-terminated and should be freed using strfreev.

Since: 2.28

getCwd

applicationCommandLineGetCwd

Arguments

:: (HasCallStack, MonadIO m, IsApplicationCommandLine a)

=> a

cmdline: a ApplicationCommandLine

-> m (Maybe [Char])

Returns: the current directory, or Nothing

Gets the working directory of the command line invocation. The string may contain non-utf8 data.

It is possible that the remote application did not send a working directory, so this may be Nothing.

The return value should not be modified or freed and is valid for as long as cmdline exists.

Since: 2.28

getEnviron

applicationCommandLineGetEnviron

Arguments

:: (HasCallStack, MonadIO m, IsApplicationCommandLine a)

=> a

cmdline: a ApplicationCommandLine

-> m [[Char]]

Returns: the environment strings, or Nothing if they were not sent

Gets the contents of the 'environ' variable of the command line invocation, as would be returned by getEnviron, ie as a Nothing-terminated list of strings in the form 'NAME=VALUE'. The strings may contain non-utf8 data.

The remote application usually does not send an environment. Use ApplicationFlagsSendEnvironment to affect that. Even with this flag set it is possible that the environment is still not available (due to invocation messages from other applications).

The return value should not be modified or freed and is valid for as long as cmdline exists.

See applicationCommandLineGetenv if you are only interested in the value of a single environment variable.

Since: 2.28

getExitStatus

applicationCommandLineGetExitStatus

Arguments

:: (HasCallStack, MonadIO m, IsApplicationCommandLine a)

=> a

cmdline: a ApplicationCommandLine

-> m Int32

Returns: the exit status

Gets the exit status of cmdline. See applicationCommandLineSetExitStatus for more information.

Since: 2.28

getIsRemote

applicationCommandLineGetIsRemote

Arguments

:: (HasCallStack, MonadIO m, IsApplicationCommandLine a)

=> a

cmdline: a ApplicationCommandLine

-> m Bool

Returns: True if the invocation was remote

Determines if cmdline represents a remote invocation.

Since: 2.28

getOptionsDict

applicationCommandLineGetOptionsDict

Arguments

:: (HasCallStack, MonadIO m, IsApplicationCommandLine a)

=> a

cmdline: a ApplicationCommandLine

-> m VariantDict

Returns: a VariantDict with the options

Gets the options there were passed to g_application_command_line().

If you did not override local_command_line() then these are the same options that were parsed according to the GOptionEntrys added to the application with applicationAddMainOptionEntries and possibly modified from your GApplication[handleLocalOptions](#signal:handleLocalOptions) handler.

If no options were sent then an empty dictionary is returned so that you don't need to check for Nothing.

Since: 2.40

getPlatformData

applicationCommandLineGetPlatformData

Arguments

:: (HasCallStack, MonadIO m, IsApplicationCommandLine a)

=> a

cmdline: ApplicationCommandLine

-> m (Maybe GVariant)

Returns: the platform data, or Nothing

Gets the platform data associated with the invocation of cmdline.

This is a GVariant dictionary containing information about the context in which the invocation occurred. It typically contains information like the current working directory and the startup notification ID.

For local invocation, it will be Nothing.

Since: 2.28

getStdin

applicationCommandLineGetStdin

Arguments

:: (HasCallStack, MonadIO m, IsApplicationCommandLine a)

=> a

cmdline: a ApplicationCommandLine

-> m InputStream

Returns: a InputStream for stdin

Gets the stdin of the invoking process.

The InputStream can be used to read data passed to the standard input of the invoking process. This doesn't work on all platforms. Presently, it is only available on UNIX when using a DBus daemon capable of passing file descriptors. If stdin is not available then Nothing will be returned. In the future, support may be expanded to other platforms.

You must only call this function once per commandline invocation.

Since: 2.34

getenv

applicationCommandLineGetenv

Arguments

:: (HasCallStack, MonadIO m, IsApplicationCommandLine a)

=> a

cmdline: a ApplicationCommandLine

-> [Char]

name: the environment variable to get

-> m Text

Returns: the value of the variable, or Nothing if unset or unsent

Gets the value of a particular environment variable of the command line invocation, as would be returned by getenv. The strings may contain non-utf8 data.

The remote application usually does not send an environment. Use ApplicationFlagsSendEnvironment to affect that. Even with this flag set it is possible that the environment is still not available (due to invocation messages from other applications).

The return value should not be modified or freed and is valid for as long as cmdline exists.

Since: 2.28

setExitStatus

applicationCommandLineSetExitStatus

Arguments

:: (HasCallStack, MonadIO m, IsApplicationCommandLine a)

=> a

cmdline: a ApplicationCommandLine

-> Int32

exitStatus: the exit status

-> m ()

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

The return value of the commandLine signal is passed to this function when the handler returns. This is the usual way of setting the exit status.

In the event that you want the remote invocation to continue running and want to decide on the exit status in the future, you can use this call. For the case of a remote invocation, the remote process will typically exit when the last reference is dropped on cmdline. The exit status of the remote process will be equal to the last value that was set with this function.

In the case that the commandline invocation is local, the situation is slightly more complicated. If the commandline invocation results in the mainloop running (ie: because the use-count of the application increased to a non-zero value) then the application is considered to have been 'successful' in a certain sense, and the exit status is always zero. If the application use count is zero, though, the exit status of the local ApplicationCommandLine is used.

Since: 2.28

Properties

arguments

No description available in the introspection data.

constructApplicationCommandLineArguments :: IsApplicationCommandLine o => GVariant -> IO (GValueConstruct o)

Construct a GValueConstruct with valid value for the “arguments” property. This is rarely needed directly, but it is used by new.

isRemote

No description available in the introspection data.

getApplicationCommandLineIsRemote :: (MonadIO m, IsApplicationCommandLine o) => o -> m Bool

Get the value of the “is-remote” property. When overloading is enabled, this is equivalent to

get applicationCommandLine #isRemote

options

No description available in the introspection data.

constructApplicationCommandLineOptions :: IsApplicationCommandLine o => GVariant -> IO (GValueConstruct o)

Construct a GValueConstruct with valid value for the “options” property. This is rarely needed directly, but it is used by new.

platformData

No description available in the introspection data.

constructApplicationCommandLinePlatformData :: IsApplicationCommandLine o => GVariant -> IO (GValueConstruct o)

Construct a GValueConstruct with valid value for the “platform-data” property. This is rarely needed directly, but it is used by new.