dbus-launch


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 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 sev-
       eral   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 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

         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/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_SES-
       SION_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_SES-
       SION_BUS_ADDRESS="something:,autolaunch:"  -  in that case if the first
       address doesn't work, processes will autolaunch. (The bus address vari-
       able 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.

              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 pass-
              ing 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 previ-
              ously-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  vari-
              ables.


       --version
              Print the version 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
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