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] [--exit-with-x11] [--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-x11
           If this option is provided, a persistent "babysitter" process will be created, and will connect to
           the X server. If it cannot do so, launching fails. If the "babysitter" process loses its X
           connection, it kills the message bus daemon, disconnecting all of its clients (which should exit in
           response). This avoids having leftover daemon processes from a user X session, after the X session
           has ended.

       --exit-with-session
           If this option is provided, a persistent "babysitter" process will be created, as if for
           --exit-with-x11. If it cannot connect to the X server, it will monitor the terminal from which
           dbus-launch was started instead, and if it gets a HUP on stdin, the message bus daemon will be
           killed. This option is not recommended, since it will consume input from the terminal where it was
           started; it is mainly provided for backwards compatibility.

       --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/