89 lines
2.8 KiB
Groff
89 lines
2.8 KiB
Groff
.\"
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.\" dbus\-uuidgen manual page.
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.\" Copyright (C) 2006 Red Hat, Inc.
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.\"
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.TH dbus\-uuidgen 1
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.SH NAME
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dbus\-uuidgen \- Utility to generate UUIDs
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.SH SYNOPSIS
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.PP
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.B dbus\-uuidgen [\-\-version] [\-\-ensure[=FILENAME]] [\-\-get[=FILENAME]]
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.SH DESCRIPTION
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The \fIdbus\-uuidgen\fP command generates or reads a universally unique ID.
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.PP
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Note that the D\-Bus UUID has no relationship to RFC 4122 and does not generate
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UUIDs compatible with that spec. Many systems have a separate command
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for that (often called "uuidgen").
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.PP
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See http://www.freedesktop.org/software/dbus/ for more information
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about D\-Bus.
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.PP
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The primary usage of \fIdbus\-uuidgen\fP is to run in the post\-install
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script of a D\-Bus package like this:
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.nf
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dbus\-uuidgen \-\-ensure
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.fi
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.PP
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This will ensure that /var/lib/dbus/machine\-id exists and has the uuid in it.
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It won't overwrite an existing uuid, since this id should remain fixed
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for a single machine until the next reboot at least.
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.PP
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The important properties of the machine UUID are that 1) it remains
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unchanged until the next reboot and 2) it is different for any two
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running instances of the OS kernel. That is, if two processes see the
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same UUID, they should also see the same shared memory, UNIX domain
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sockets, local X displays, localhost.localdomain resolution, process
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IDs, and so forth.
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.PP
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If you run \fIdbus\-uuidgen\fP with no options it just prints a new uuid made
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up out of thin air.
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.PP
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If you run it with \-\-get, it prints the machine UUID by default, or
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the UUID in the specified file if you specify a file.
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.PP
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If you try to change an existing machine\-id on a running system, it will
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probably result in bad things happening. Don't try to change this file. Also,
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don't make it the same on two different systems; it needs to be different
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anytime there are two different kernels running.
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.PP
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The UUID should be different on two different virtual machines,
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because there are two different kernels.
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.SH OPTIONS
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The following options are supported:
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.TP
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.I "\-\-get[=FILENAME]"
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If a filename is not given, defaults to localstatedir/lib/dbus/machine\-id
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(localstatedir is usually /var). If this file exists and is valid, the
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uuid in the file is printed on stdout. Otherwise, the command exits
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with a nonzero status.
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.TP
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.I "\-\-ensure[=FILENAME]"
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If a filename is not given, defaults to localstatedir/lib/dbus/machine\-id
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(localstatedir is usually /var). If this file exists then it will be
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validated, and a failure code returned if it contains the wrong thing.
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If the file does not exist, it will be created with a new uuid in it.
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On success, prints no output.
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.TP
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.I "\-\-version"
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Print the version of dbus\-uuidgen
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.SH AUTHOR
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See http://www.freedesktop.org/software/dbus/doc/AUTHORS
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.SH BUGS
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Please send bug reports to the D\-Bus mailing list or bug tracker,
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see http://www.freedesktop.org/software/dbus/
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