uuidd — UUID generation daemon


uuidd [options]


The uuidd daemon is used by the UUID library to generate universally unique identifiers (UUIDs), especially time-based UUIDs, in a secure and guaranteed-unique fashion, even in the face of large numbers of threads running on different CPUs trying to grab UUIDs.


−d, −−debug

Run uuidd in debugging mode. This prevents uuidd from running as a daemon.

−F, −−no−fork

Do not daemonize using a double-fork.

−k, −−kill

If currently a uuidd daemon is running, kill it.

−n, −−uuids number

When issuing a test request to a running uuidd, request a bulk response of number UUIDs.

−P, −−no−pid

Do not create a pid file.

−p, −−pid path

Specify the pathname where the pid file should be written. By default, the pid file is written to /run/uuidd/

−q, −−quiet

Suppress some failure messages.

−r, −−random

Test uuidd by trying to connect to a running uuidd daemon and request it to return a random-based UUID.

−S, −−socket−activation

Do not create a socket but instead expect it to be provided by the calling process. This implies −−no−fork and −−no−pid. This option is intended to be used only with systemd(1). It needs to be enabled with a configure option.

−s, −−socket path

Make uuidd use this pathname for the unix-domain socket. By default, the pathname used is /run/uuidd/request. This option is primarily for debugging purposes, since the pathname is hard-coded in the libuuid library.

−T, −−timeout number

Make uuidd exit after number seconds of inactivity.

−t, −−time

Test uuidd by trying to connect to a running uuidd daemon and request it to return a time-based UUID.

−V, −−version

Output version information and exit.

−h, −−help

Display help screen and exit.


Start up a daemon, print 42 random keys, and then stop the daemon:

uuidd −p /tmp/ −s /tmp/uuidd.socket
uuidd −d −r −n 42 −s /tmp/uuidd.socket
uuidd −d −k −s /tmp/uuidd.socket


The uuidd daemon was written by Theodore Ts'o <>.


uuid(3), uuidgen(1)


The uuidd daemon is part of the util-linux package and is available from the Linux Kernel Archive

  Copyright 2007 by Theodore Ts'o.  All Rights Reserved.
This file may be copied under the terms of the GNU Public License.