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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
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().
Since 2.28
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.
Since 2.28
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.
the environment
strings, or NULL if they were not sent.
[array zero-terminated=1][transfer none]
Since 2.28
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.
Since 2.40
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.
Since 2.34
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.
Since 2.36
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.
Since 2.28
gboolean
g_application_command_line_get_is_remote
(GApplicationCommandLine *cmdline);
Determines if cmdline
represents a remote invocation.
Since 2.28
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.
Since 2.28
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.
Since 2.28
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.
Since 2.28
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.
Since 2.28
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.
Since 2.28
typedef struct _GApplicationCommandLine GApplicationCommandLine;
GApplicationCommandLine is an opaque data structure and can only be accessed using the following functions.
“arguments” property“arguments” GVariant *
The commandline that caused this ::command-line signal emission.
Flags: Write / Construct Only
Allowed values: GVariant<aay>
Default value: NULL
“is-remote” property“is-remote” gboolean
TRUE if this is a remote commandline.
Flags: Read
Default value: FALSE
“options” property“options” GVariant *
The options sent along with the commandline.
Flags: Write / Construct Only
Allowed values: GVariant<a{sv}>
Default value: NULL
“platform-data” property“platform-data” GVariant *
Platform-specific data for the commandline.
Flags: Write / Construct Only
Allowed values: GVariant<a{sv}>
Default value: NULL