uuidd8
Uuid generation daemon
Usage
uuidd [options]
Overview
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.
Options
-C, --cont-clock[=number[hd]]
Activate continuous clock handling for time-based UUIDs. uuidd could use all possible clock values, beginning with the daemon’s start time. The optional argument can be used to set a value for 'max_clock_offset'. This guarantees that a clock value of a UUID will always be within the range of 'max_clock_offset'.
The option -C or --cont-clock (without an argument) enables the feature with a default 'max_clock_offset' of 2 hours.
The option -Cnumber or --cont-clock=number enables the feature with a 'max_clock_offset' of number seconds. In case of an appended h or d, number is understood in hours or days. The minimum value is 60 seconds, the maximum value is 365 days.
-
-d, --debug -
Run
uuiddin debugging mode. This preventsuuiddfrom 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/uuidd.pid.
-
-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-forkand--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
libuuidlibrary.
-
-T, --timeout number -
Make
uuiddexit after number seconds of inactivity.
-
-t, --time -
Test
uuiddby 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 -
Display version and exit.
Examples
Start up a daemon, print 42 random keys, and then stop the daemon:
uuidd -p /tmp/uuidd.pid -s /tmp/uuidd.socket uuidd -d -r -n 42 -s /tmp/uuidd.socket uuidd -d -k -s /tmp/uuidd.socket
History
- Arch Linux 2026-11-01: the text shown here
- Debian 13 (Trixie)
- Debian 12 (Bookworm)
- Debian 11 (Bullseye)
- Debian 10 (Buster)
- Debian 9 (Stretch)
- Debian 8 (Jessie)
- Debian 7 (Wheezy)
- Debian 6.0 (Squeeze)
- Debian 5.0 (Lenny)
--debug since Debian 8 (Jessie);
--help since Debian 7 (Wheezy);
--kill since Debian 7 (Wheezy);
--no-fork since Debian 8 (Jessie);
--no-pid since Debian 8 (Jessie);
--pid since Debian 7 (Wheezy);
--quiet since Debian 8 (Jessie);
--random since Debian 7 (Wheezy);
--socket since Debian 7 (Wheezy);
--socket-activation since Debian 8 (Jessie);
--time since Debian 7 (Wheezy);
--timeout since Debian 7 (Wheezy);
--uuids since Debian 7 (Wheezy);
--version since Debian 7 (Wheezy);
-F since Debian 8 (Jessie);
-P since Debian 8 (Jessie);
-S since Debian 8 (Jessie);
-T since Debian 7 (Wheezy);
-V since Debian 7 (Wheezy);
-h since Debian 7 (Wheezy);
-n since Debian 7 (Wheezy);
-p since Debian 7 (Wheezy);
-q since Debian 7 (Wheezy);
-s since Debian 7 (Wheezy).
--cont-clock until Debian 13 (Trixie);
-C until Debian 13 (Trixie).