dbus-uuidgen

dbus-uuidgen(1)                                                dbus-uuidgen(1)



NAME
       dbus-uuidgen - Utility to generate UUIDs

SYNOPSIS
       dbus-uuidgen [--version] [--ensure[=FILENAME]] [--get[=FILENAME]]


DESCRIPTION
       The dbus-uuidgen command generates or reads a universally unique ID.


       Note  that  the D-Bus UUID has no relationship to RFC 4122 and does not
       generate UUIDs compatible with that spec. Many systems have a  separate
       command for that (often called "uuidgen").


       See   http://www.freedesktop.org/software/dbus/  for  more  information
       about D-Bus.


       The primary usage of dbus-uuidgen is to run in the post-install  script
       of a D-Bus package like this:
         dbus-uuidgen --ensure


       This  will ensure that /var/lib/dbus/machine-id exists and has the uuid
       in it.  It won't overwrite an  existing  uuid,  since  this  id  should
       remain fixed for a single machine until the next reboot at least.


       The  important  properties  of  the machine UUID are that 1) it remains
       unchanged until the next reboot and 2) it is different for any two run‐
       ning instances of the OS kernel. That is, if two processes see the same
       UUID, they should also see the same shared memory, UNIX domain sockets,
       local X displays, localhost.localdomain resolution, process IDs, and so
       forth.


       If you run dbus-uuidgen with no options it just prints a new uuid  made
       up out of thin air.


       If you run it with --get, it prints the machine UUID by default, or the
       UUID in the specified file if you specify a file.


       If you try to change an existing machine-id on  a  running  system,  it
       will  probably result in bad things happening. Don't try to change this
       file. Also, don't make it the same on two different systems;  it  needs
       to be different anytime there are two different kernels running.


       The UUID should be different on two different virtual machines, because
       there are two different kernels.


OPTIONS
       The following options are supported:

       --get[=FILENAME]
              If  a  filename  is   not   given,   defaults   to   localstate‐
              dir/lib/dbus/machine-id (localstatedir is usually /var). If this
              file exists and is valid, the uuid in the  file  is  printed  on
              stdout. Otherwise, the command exits with a nonzero status.


       --ensure[=FILENAME]
              If   a   filename   is   not   given,  defaults  to  localstate‐
              dir/lib/dbus/machine-id (localstatedir is usually /var). If this
              file  exists  then  it  will  be  validated,  and a failure code
              returned if it contains the wrong thing.  If the file  does  not
              exist,  it  will  be created with a new uuid in it.  On success,
              prints no output.


       --version
              Print the version of dbus-uuidgen


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-uuidgen(1)