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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/AUTHORS

BUGS

   Please send bug reports to the D-Bus mailing list or bug tracker, see
   http://www.freedesktop.org/software/dbus/



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