| .\" |
| .\" dbus\-uuidgen manual page. |
| .\" Copyright (C) 2006 Red Hat, Inc. |
| .\" |
| .TH dbus\-uuidgen 1 |
| .SH NAME |
| dbus\-uuidgen \- Utility to generate UUIDs |
| .SH SYNOPSIS |
| .PP |
| .B dbus\-uuidgen [\-\-version] [\-\-ensure[=FILENAME]] [\-\-get[=FILENAME]] |
| |
| .SH DESCRIPTION |
| |
| The \fIdbus\-uuidgen\fP command generates or reads a universally unique ID. |
| |
| .PP |
| 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"). |
| |
| .PP |
| See http://www.freedesktop.org/software/dbus/ for more information |
| about D\-Bus. |
| |
| .PP |
| The primary usage of \fIdbus\-uuidgen\fP is to run in the post\-install |
| script of a D\-Bus package like this: |
| .nf |
| dbus\-uuidgen \-\-ensure |
| .fi |
| |
| .PP |
| 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. |
| |
| .PP |
| 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. |
| |
| .PP |
| If you run \fIdbus\-uuidgen\fP with no options it just prints a new uuid made |
| up out of thin air. |
| |
| .PP |
| 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. |
| |
| .PP |
| 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. |
| |
| .PP |
| The UUID should be different on two different virtual machines, |
| because there are two different kernels. |
| |
| .SH OPTIONS |
| The following options are supported: |
| .TP |
| .I "\-\-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. |
| |
| .TP |
| .I "\-\-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. |
| |
| .TP |
| .I "\-\-version" |
| Print the version of dbus\-uuidgen |
| |
| .SH AUTHOR |
| See http://www.freedesktop.org/software/dbus/doc/AUTHORS |
| |
| .SH BUGS |
| Please send bug reports to the D\-Bus mailing list or bug tracker, |
| see http://www.freedesktop.org/software/dbus/ |
