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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 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 spec-
       ify 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.


       --ensure[=FILENAME]
              If  a  filename  is  not  given, defaults to localstatedir/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)