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DBUS-LAUNCH(1)			 User Commands			DBUS-LAUNCH(1)

NAME
       dbus-launch - Utility to	start a	message	bus from a shell script

SYNOPSIS
       dbus-launch [--version] [--help]	[--sh-syntax] [--csh-syntax]
		   [--auto-syntax] [--binary-syntax] [--close-stderr]
		   [--exit-with-session] [--autolaunch=MACHINEID]
		   [--config-file=FILENAME] [PROGRAM] [ARGS...]

DESCRIPTION
       The dbus-launch command is used to start	a session bus instance of
       dbus-daemon from	a shell	script.	It would normally be called from a
       user's login scripts. Unlike the	daemon itself, dbus-launch exits, so
       backticks or the	$() construct can be used to read information from
       dbus-launch.

       With no arguments, dbus-launch will launch a session bus	instance and
       print the address and PID of that instance to standard output.

       You may specify a program to be run; in this case, dbus-launch will
       launch a	session	bus instance, set the appropriate environment
       variables so the	specified program can find the bus, and	then execute
       the specified program, with the specified arguments. See	below for
       examples.

       If you launch a program,	dbus-launch will not print the information
       about the new bus to standard output.

       When dbus-launch	prints bus information to standard output, by default
       it is in	a simple key-value pairs format. However, you may request
       several alternate syntaxes using	the --sh-syntax, --csh-syntax,
       --binary-syntax,	or --auto-syntax options. Several of these cause
       dbus-launch to emit shell code to set up	the environment.

       With the	--auto-syntax option, dbus-launch looks	at the value of	the
       SHELL environment variable to determine which shell syntax should be
       used. If	SHELL ends in "csh", then csh-compatible code is emitted;
       otherwise Bourne	shell code is emitted. Instead of passing
       --auto-syntax, you may explicitly specify a particular one by using
       --sh-syntax for Bourne syntax, or --csh-syntax for csh syntax. In
       scripts,	it's more robust to avoid --auto-syntax	and you	hopefully know
       which shell your	script is written in.

       See http://www.freedesktop.org/software/dbus/ for more information
       about D-Bus. See	also the man page for dbus-daemon.

EXAMPLES
       Distributions running dbus-launch as part of a standard X session
       should run dbus-launch --exit-with-session after	the X server has
       started and become available, as	a wrapper around the "main" X client
       (typically a session manager or window manager),	as in these examples:

       dbus-launch --exit-with-session gnome-session

       dbus-launch --exit-with-session openbox

       dbus-launch --exit-with-session ~/.xsession

       If your distribution does not do	this, you can achieve similar results
       by running your session or window manager in the	same way in a script
       run by your X session, such as ~/.xsession, ~/.xinitrc or ~/.Xclients.

       To start	a D-Bus	session	within a text-mode session, do not use
       dbus-launch. Instead, see dbus-run-session(1).

	     ##	test for an existing bus daemon, just to be safe
	     if	test -z	"$DBUS_SESSION_BUS_ADDRESS" ; then
		 ## if not found, launch a new one
		 eval `dbus-launch --sh-syntax`
		 echo "D-Bus per-session daemon	address	is: $DBUS_SESSION_BUS_ADDRESS"
	     fi

       Note that in this case, dbus-launch will	exit, and dbus-daemon will not
       be terminated automatically on logout.

AUTOMATIC LAUNCHING
       If DBUS_SESSION_BUS_ADDRESS is not set for a process that tries to use
       D-Bus, by default the process will attempt to invoke dbus-launch	with
       the --autolaunch	option to start	up a new session bus or	find the
       existing	bus address on the X display or	in a file in
       ~/.dbus/session-bus/

       Whenever	an autolaunch occurs, the application that had to start	a new
       bus will	be in its own little world; it can effectively end up starting
       a whole new session if it tries to use a	lot of bus services. This can
       be suboptimal or	even totally broken, depending on the app and what it
       tries to	do.

       There are two common reasons for	autolaunch. One	is ssh to a remote
       machine.	The ideal fix for that would be	forwarding of
       DBUS_SESSION_BUS_ADDRESS	in the same way	that DISPLAY is	forwarded. In
       the meantime, you can edit the session.conf config file to have your
       session bus listen on TCP, and manually set DBUS_SESSION_BUS_ADDRESS,
       if you like.

       The second common reason	for autolaunch is an su	to another user, and
       display of X applications running as the	second user on the display
       belonging to the	first user. Perhaps the	ideal fix in this case would
       be to allow the second user to connect to the session bus of the	first
       user, just as they can connect to the first user's display. However, a
       mechanism for that has not been coded.

       You can always avoid autolaunch by manually setting
       DBUS_SESSION_BUS_ADDRESS. Autolaunch happens because the	default
       address if none is set is "autolaunch:",	so if any other	address	is set
       there will be no	autolaunch. You	can however include autolaunch in an
       explicit	session	bus address as a fallback, for example
       DBUS_SESSION_BUS_ADDRESS="something:,autolaunch:" - in that case	if the
       first address doesn't work, processes will autolaunch. (The bus address
       variable	contains a comma-separated list	of addresses to	try.)

       The --autolaunch	option is considered an	internal implementation	detail
       of libdbus, and in fact there are plans to change it. There's no	real
       reason to use it	outside	of the libdbus implementation anyhow.

OPTIONS
       The following options are supported:

       --auto-syntax
	   Choose --csh-syntax or --sh-syntax based on the SHELL environment
	   variable.

       --binary-syntax
	   Write to stdout a nul-terminated bus	address, then the bus PID as a
	   binary integer of size sizeof(pid_t), then the bus X	window ID as a
	   binary integer of size sizeof(long).	Integers are in	the machine's
	   byte	order, not network byte	order or any other canonical byte
	   order.

       --close-stderr
	   Close the standard error output stream before starting the D-Bus
	   daemon. This	is useful if you want to capture dbus-launch error
	   messages but	you don't want dbus-daemon to keep the stream open to
	   your	application.

       --config-file=FILENAME
	   Pass	--config-file=FILENAME to the bus daemon, instead of passing
	   it the --session argument. See the man page for dbus-daemon

       --csh-syntax
	   Emit	csh compatible code to set up environment variables.

       --exit-with-session
	   If this option is provided, a persistent "babysitter" process will
	   be created that watches stdin for HUP and tries to connect to the X
	   server. If this process gets	a HUP on stdin or loses	its X
	   connection, it kills	the message bus	daemon.

       --autolaunch=MACHINEID
	   This	option implies that dbus-launch	should scan for	a
	   previously-started session and reuse	the values found there.	If no
	   session is found, it	will start a new session. The
	   --exit-with-session option is implied if --autolaunch is given.
	   This	option is for the exclusive use	of libdbus, you	do not want to
	   use it manually. It may change in the future.

       --sh-syntax
	   Emit	Bourne-shell compatible	code to	set up environment variables.

       --version
	   Print the version of	dbus-launch

       --help
	   Print the help info of dbus-launch

NOTES
       If you run dbus-launch myapp (with any other options), dbus-daemon will
       not exit	when myapp terminates: this is because myapp is	assumed	to be
       part of a larger	session, rather	than a session in its own right.

AUTHOR
       See http://www.freedesktop.org/software/dbus/doc/AUTHORS

BUGS
       Please send bug reports to the D-Bus mailing list or bug	tracker, see
       http://www.freedesktop.org/software/dbus/

D-Bus 1.10.16			  07/02/2017			DBUS-LAUNCH(1)

NAME | SYNOPSIS | DESCRIPTION | EXAMPLES | AUTOMATIC LAUNCHING | OPTIONS | NOTES | AUTHOR | BUGS

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