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dbus-uuidgen(1)                                General Commands Manual                                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 running 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 resolu‐
       tion, 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 happen‐
       ing. Don't try to change this file. Also, don't make it the same on two different systems; it needs to be dif‐
       ferent 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 localstatedir/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 com‐
              mand exits with a nonzero status.



       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/soft‐
       ware/dbus/



                                                                                                      dbus-uuidgen(1)