Scroll to navigation

UUIDD(8) System Administration UUIDD(8)


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 {runstatedir}/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 {runstatedir}/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.

-h, --help

Display help text and exit.

-V, --version

Print version 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)


For bug reports, use the issue tracker at <>.


The uuidd command is part of the util-linux package which can be downloaded from Linux Kernel Archive <>.

2022-08-04 util-linux 2.38.1