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.


Run uuidd in debugging mode. This prevents uuidd from running as a daemon.
Do not daemonize using a double-fork.
If currently a uuidd daemon is running, kill it.
When issuing a test request to a running uuidd, request a bulk response of number UUIDs.
Do not create a pid file.
Specify the pathname where the pid file should be written. By default, the pid file is written to /run/uuidd/
Suppress some failure messages.
Test uuidd by trying to connect to a running uuidd daemon and request it to return a random-based UUID.
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.
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.
Make uuidd exit after number seconds of inactivity.
Test uuidd by trying to connect to a running uuidd daemon and request it to return a time-based UUID.
Output version information and exit.
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.

July 2014 util-linux