Provided by: dbus-x11_1.4.18-1ubuntu1_amd64 bug

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=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 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/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

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)