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/