1DBUS-UUIDGEN(1)                  User Commands                 DBUS-UUIDGEN(1)
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NAME

6       dbus-uuidgen - Utility to generate UUIDs
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SYNOPSIS

9       dbus-uuidgen [--version] [--ensure [=FILENAME]] [--get [=FILENAME]]
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DESCRIPTION

13       The dbus-uuidgen command generates or reads a universally unique ID.
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15       Note that the D-Bus UUID has no relationship to RFC 4122 and does not
16       generate UUIDs compatible with that spec. Many systems have a separate
17       command for that (often called "uuidgen").
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19       See http://www.freedesktop.org/software/dbus/ for more information
20       about D-Bus.
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22       The primary usage of dbus-uuidgen is to run in the post-install script
23       of a D-Bus package like this:
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25             dbus-uuidgen --ensure
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27       This will ensure that /var/lib/dbus/machine-id exists and has the uuid
28       in it. It won't overwrite an existing uuid, since this id should remain
29       fixed for a single machine until the next reboot at least.
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31       The important properties of the machine UUID are that 1) it remains
32       unchanged until the next reboot and 2) it is different for any two
33       running instances of the OS kernel. That is, if two processes see the
34       same UUID, they should also see the same shared memory, UNIX domain
35       sockets, local X displays, localhost.localdomain resolution, process
36       IDs, and so forth.
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38       If you run dbus-uuidgen with no options it just prints a new uuid made
39       up out of thin air.
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41       If you run it with --get, it prints the machine UUID by default, or the
42       UUID in the specified file if you specify a file.
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44       If you try to change an existing machine-id on a running system, it
45       will probably result in bad things happening. Don't try to change this
46       file. Also, don't make it the same on two different systems; it needs
47       to be different anytime there are two different kernels running.
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49       The UUID should be different on two different virtual machines, because
50       there are two different kernels.
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OPTIONS

53       The following options are supported:
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55       --get[=FILENAME]
56           If a filename is not given, defaults to
57           localstatedir/lib/dbus/machine-id (localstatedir is usually /var).
58           If this file exists and is valid, the uuid in the file is printed
59           on stdout. Otherwise, the command exits with a nonzero status.
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61       --ensure[=FILENAME]
62           If a filename is not given, defaults to
63           localstatedir/lib/dbus/machine-id (localstatedir is usually /var).
64           If this file exists then it will be validated, and a failure code
65           returned if it contains the wrong thing. If the file does not
66           exist, it will be created with a new uuid in it. On success, prints
67           no output.
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69       --version
70           Print the version of dbus-uuidgen
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AUTHOR

73       See http://www.freedesktop.org/software/dbus/doc/AUTHORS
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BUGS

76       Please send bug reports to the D-Bus mailing list or bug tracker, see
77       http://www.freedesktop.org/software/dbus/
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81D-Bus 1.12.16                     01/31/2020                   DBUS-UUIDGEN(1)
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