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/AUTHORSBUGS
Please send bug reports to the D-Bus mailing list or bug tracker, see
http://www.freedesktop.org/software/dbus/D-Bus 1.12.28 01/10/2025 DBUS-UUIDGEN(1)
