GApplicationCommandLine: GIO Reference Manual

## GApplicationCommandLine GApplicationCommandLine — A command-line invocation of an application |

## Functions

gchar ** | g_application_command_line_get_arguments ()
const gchar * | g_application_command_line_get_cwd ()
const gchar * const * | g_application_command_line_get_environ ()
GVariantDict * | g_application_command_line_get_options_dict ()
GInputStream * | g_application_command_line_get_stdin ()
GFile * | g_application_command_line_create_file_for_arg ()
const gchar * | g_application_command_line_getenv ()
gboolean | g_application_command_line_get_is_remote ()
GVariant * | g_application_command_line_get_platform_data ()
void | g_application_command_line_set_exit_status ()
int | g_application_command_line_get_exit_status ()
void | g_application_command_line_print ()
void | g_application_command_line_printerr ()

## Properties

GVariant * | arguments | Write / Construct Only
gboolean | is-remote | Read
GVariant * | options | Write / Construct Only
GVariant * | platform-data | Write / Construct Only

## Types and Values

| GApplicationCommandLine
struct | GApplicationCommandLineClass

## Object Hierarchy

        GObject
        ╰── GApplicationCommandLine

## Includes

    #include <gio/gio.h>

## Description

GApplicationCommandLine represents a command-line invocation of an application. It is created by GApplication and emitted in the “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 GOptionContext command-line parsing API, with the `g_application_command_line_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. 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 GApplicationCommandLine (and the “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 “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.

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    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.

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    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 “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.

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    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 “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

## Functions

### g_application_command_line_get_arguments ()

    gchar **
    g_application_command_line_get_arguments
                                   (GApplicationCommandLine *cmdline,
                                    int *argc);

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 GOptionContext, you must use `g_option_context_parse_strv()`.

The return value is `NULL`-terminated and should be freed using `g_strfreev()`.

#### Parameters

cmdline | a GApplicationCommandLine |
argc | the length of the arguments array, or `NULL`. | [out][optional]

#### Returns

the string array containing the arguments (the argv).

[array length=argc][transfer full]

Since: 2.28

### g_application_command_line_get_cwd ()

    const gchar *
    g_application_command_line_get_cwd (GApplicationCommandLine *cmdline);

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 `NULL`.

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

#### Parameters

cmdline | a GApplicationCommandLine |

#### Returns

the current directory, or `NULL`.

[nullable][type filename]

Since: 2.28

### g_application_command_line_get_environ ()

    const gchar * const *
    g_application_command_line_get_environ
                                   (GApplicationCommandLine *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.

The remote application usually does not send an environment. Use `G_APPLICATION_SEND_ENVIRONMENT` 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 `g_application_command_line_getenv()` if you are only interested in the value of a single environment variable.

#### Parameters

cmdline | a GApplicationCommandLine |

#### Returns

the environment strings, or `NULL` if they were not sent.

[array zero-terminated=1][transfer none]

Since: 2.28

### g_application_command_line_get_options_dict ()

    GVariantDict *
    g_application_command_line_get_options_dict
                                   (GApplicationCommandLine *cmdline);

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 `g_application_add_main_option_entries()` and possibly modified from your GApplication::handle-local-options handler.

If no options were sent then an empty dictionary is returned so that you don't need to check for `NULL`.

#### Parameters

cmdline | a GApplicationCommandLine |

#### Returns

a GVariantDict with the options.

[transfer none]

Since: 2.40

### g_application_command_line_get_stdin ()

    GInputStream *
    g_application_command_line_get_stdin (GApplicationCommandLine *cmdline);

Gets the stdin of the invoking process.

The GInputStream 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 `NULL` will be returned. In the future, support may be expanded to other platforms.

You must only call this function once per commandline invocation.

#### Parameters

cmdline | a GApplicationCommandLine |

#### Returns

a GInputStream for stdin.

[transfer full]

Since: 2.34

### g_application_command_line_create_file_for_arg ()

    GFile *
    g_application_command_line_create_file_for_arg
                                   (GApplicationCommandLine *cmdline,
                                    const gchar *arg);

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

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

#### Parameters

cmdline | a GApplicationCommandLine |
arg | an argument from `cmdline` |

#### Returns

a new GFile.

[transfer full]

Since: 2.36

### g_application_command_line_getenv ()

    const gchar *
    g_application_command_line_getenv (GApplicationCommandLine *cmdline,
                                       const gchar *name);

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

The remote application usually does not send an environment. Use `G_APPLICATION_SEND_ENVIRONMENT` 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.

#### Parameters

cmdline | a GApplicationCommandLine |
name | the environment variable to get |

#### Returns

the value of the variable, or `NULL` if unset or unsent

Since: 2.28

### g_application_command_line_get_is_remote ()

    gboolean
    g_application_command_line_get_is_remote
                                   (GApplicationCommandLine *cmdline);

Determines if `cmdline` represents a remote invocation.

#### Parameters

cmdline | a GApplicationCommandLine |

#### Returns

`TRUE` if the invocation was remote

Since: 2.28

### g_application_command_line_get_platform_data ()

    GVariant *
    g_application_command_line_get_platform_data
                                   (GApplicationCommandLine *cmdline);

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 `NULL`.

#### Parameters

cmdline | GApplicationCommandLine |

#### Returns

the platform data, or `NULL`.

[nullable]

Since: 2.28

### g_application_command_line_set_exit_status ()

    void
    g_application_command_line_set_exit_status
                                   (GApplicationCommandLine *cmdline,
                                    int exit_status);

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

The return value of the “command-line” 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 GApplicationCommandLine is used.

#### Parameters

cmdline | a GApplicationCommandLine |
exit_status | the exit status |

Since: 2.28

### g_application_command_line_get_exit_status ()

    int
    g_application_command_line_get_exit_status
                                   (GApplicationCommandLine *cmdline);

Gets the exit status of `cmdline` . See `g_application_command_line_set_exit_status()` for more information.

#### Parameters

cmdline | a GApplicationCommandLine |

#### Returns

the exit status

Since: 2.28

### g_application_command_line_print ()

    void
    g_application_command_line_print (GApplicationCommandLine *cmdline,
                                      const gchar *format,
                                      ...);

Formats a message and prints it using the stdout print handler in the invoking process.

If `cmdline` is a local invocation then this is exactly equivalent to `g_print()`. If `cmdline` is remote then this is equivalent to calling `g_print()` in the invoking process.

#### Parameters

cmdline | a GApplicationCommandLine |
format | a printf-style format string |
... | arguments, as per `format` |

Since: 2.28

### g_application_command_line_printerr ()

    void
    g_application_command_line_printerr (GApplicationCommandLine *cmdline,
                                         const gchar *format,
                                         ...);

Formats a message and prints it using the stderr print handler in the invoking process.

If `cmdline` is a local invocation then this is exactly equivalent to `g_printerr()`. If `cmdline` is remote then this is equivalent to calling `g_printerr()` in the invoking process.

#### Parameters

cmdline | a GApplicationCommandLine |
format | a printf-style format string |
... | arguments, as per `format` |

Since: 2.28

## Types and Values

### GApplicationCommandLine

    typedef struct _GApplicationCommandLine GApplicationCommandLine;

GApplicationCommandLine is an opaque data structure and can only be accessed using the following functions.

### struct GApplicationCommandLineClass

    struct GApplicationCommandLineClass {
    };

The GApplicationCommandLineClass contains private data only.

Since: 2.28

## Property Details

### The `“arguments”` property

      “arguments”                GVariant *

The commandline that caused this ::command-line signal emission.

Flags: Write / Construct Only

Allowed values: GVariant<aay>

Default value: NULL

### The `“is-remote”` property

      “is-remote”                gboolean

TRUE if this is a remote commandline.

Flags: Read

Default value: FALSE

### The `“options”` property

      “options”                  GVariant *

The options sent along with the commandline.

Flags: Write / Construct Only

Allowed values: GVariant<a{sv}>

Default value: NULL

### The `“platform-data”` property

      “platform-data”            GVariant *

Platform-specific data for the commandline.

Flags: Write / Construct Only

Allowed values: GVariant<a{sv}>

Default value: NULL

## See Also

GApplication