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DBUS-UUIDGEN(1)			 User Commands		       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	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
	   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 command 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/

D-Bus 1.10.16			  07/02/2017		       DBUS-UUIDGEN(1)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | AUTHOR | BUGS

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