dbus-uuidgen(1)
Namedbus-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.
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 --ensureThiswill ensure that /var/lib/dbus/machine-id exists and has the uuid init. It won't overwrite an existing uuid, since this id should remainfixed for asingle machine until the next reboot at least.
The important properties of the machine UUID are that 1) it remainsunchanged until the next reboot and 2) it is different for any tworunning instances ofthe OS kernel. That is, if two processes see the same UUID, they shouldalso 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. This is similar to the regular "uuidgen" command.
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.
The D-Bus UUID has no relationship to RFC 4122 and does not generate UUIDs compatible with that spec.
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 changethis file. Also, don'tmake it the same on two different systems; it needs to be differentanytime there are two different kernels running.
Options
The following options are supported:
--get[=FILENAME]If a filename is not given, defaults tolocalstatedir/lib/dbus/machine-id (localstatedir is usually /var). Ifthis file exists and is valid, the uuid inthe file is printed on stdout. Otherwise, the command exits with anonzero status.--ensure[=FILENAME]If a filename is not given, defaults tolocalstatedir/lib/dbus/machine-id (localstatedir is usually /var). Ifthis file exists then it will be validated,and a failure code returned if it contains the wrong thing. If the filedoes not exist, it will be created with a new uuid in it. On success,prints no output.--versionPrint the version of dbus-uuidgenAuthor
See http://www.freedesktop.org/software/dbus/doc/AUTHORS
Bugs
Please send bug reports to the D-Bus mailing list or bug tracker, seehttp://www.freedesktop.org/software/dbus/
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