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 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

SEE ALSO

uuid(3), uuidgen(1)

REPORTING BUGS

For bug reports, use the issue tracker at

AVAILABILITY

The uuidd command is part of the util-linux package which can be downloaded from