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


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


       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

       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

       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 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  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"

       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.


       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-

       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.


       The following options are supported:

              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 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.

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

              Emit csh compatible code to set up environment variables.

              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.

              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.

              Emit  Bourne-shell  compatible  code  to  set   up   environment

              Print the version of dbus-launch




       Please  send  bug reports to the D-Bus mailing list or bug tracker, see