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/