uuidd.8

UUIDD

NAME
SYNOPSIS
DESCRIPTION
OPTIONS
EXAMPLE
AUTHOR
SEE ALSO
REPORTING BUGS
AVAILABILITY

---

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 guaranteed−unique fashion, even in the face of large numbers of threads running on different CPUs trying to grab UUIDs.

OPTIONS

−C, −−cont−clock[=time]

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 the max_clock_offset. This gurantees, that a clock value of a UUID will always be within the range of the max_clock_offset.

The option −C or −−cont−clock enables the feature with a default max_clock_offset of 2 hours.

The option −C<NUM>[hd] or −−cont−clock=<NUM>[hd] enables the feature with a max_clock_offset of NUM seconds. In case of an appended h or d, the NUM value is read 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 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−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.

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 at <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/>.

---