dbus-launch(1)						      General Commands Manual						    dbus-launch(1)

NAME

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

SYNOPSIS

       dbus-launch  [--version]  [--sh-syntax]	[--csh-syntax] [--auto-syntax] [--exit-with-session] [--autolaunch=MACHINEID] [--config-file=FILE-
       NAME] [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  vari-
       ables so the specified program can find the bus, and then execute the specified program, with the specified arguments.  See below for exam-
       ples.

       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-syn-
       tax, you may explicity 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.

       Here is an example of how to use dbus-launch with an sh-compatible shell to start the per-session bus daemon:

	 ## 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 --exit-with-session`
	     echo "D-Bus per-session daemon address is: $DBUS_SESSION_BUS_ADDRESS"
	 fi

       You might run something like that in your login scripts.

       Another way to use dbus-launch is to run your main session program, like so:

       dbus-launch gnome-session

       The above would likely be appropriate for ~/.xsession or ~/.Xclients.

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/ses-
       sion-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_SES-
       SION_BUS_ADDRESS in the same way that DISPLAY is forwarded.  In the meantime, you can edit the session.conf config file to have	your  ses-
       sion 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, pro-
       cesses 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

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/

																    dbus-launch(1)