UUIDD(8) System Administration UUIDD(8) NAME uuidd - UUID generation daemon SYNOPSIS uuidd [options] DESCRIPTION The uuidd daemon is used by the UUID library to generate universally unique identifiers (UUIDs), especially time-based UUIDs, in a secure and guaran- teed-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_off- set'. 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 uuidd in debugging mode. This prevents uuidd from running as a dae- mon. -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-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 pri- marily 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 Display version and exit. EXAMPLE 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 AUTHOR The uuidd daemon was written by Theodore Ts'o <tytso@mit.edu>. SEE ALSO uuid(3), uuidgen(1) REPORTING BUGS For bug reports, use the issue tracker <https://github.com/util-linux/util-linux/issues>. AVAILABILITY The uuidd command is part of the util-linux package which can be downloaded from Linux Kernel Archive <https://www.kernel.org/pub/linux/utils/util-linux/>. util-linux 2.42.2 2026-06-16 UUIDD(8)
NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXAMPLE | AUTHOR | SEE ALSO | REPORTING BUGS | AVAILABILITY
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