1.\" Copyright (c) 2002 Marcel Moolenaar 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 15.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 16.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 17.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 18.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 19.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 20.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 21.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 22.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 23.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 24.\" 25.\" $FreeBSD$ 26.\" 27.Dd May 23, 2012 28.Dt UUIDGEN 1 29.Os 30.Sh NAME 31.Nm uuidgen 32.Nd generate universally unique identifiers 33.Sh SYNOPSIS 34.Nm 35.Op Fl 1 36.Op Fl r 37.Op Fl n Ar count 38.Op Fl o Ar filename 39.Sh DESCRIPTION 40The 41.Nm 42utility by default generates a single DCE version 1 43universally unique identifier (UUID), 44also known as a globally unique identifier (GUID). 45The UUID is written to stdout by default. 46The following options can be used to change the behaviour of 47.Nm : 48.Bl -tag -width indent 49.It Fl 1 50This option only has effect if multiple identifiers are to be generated and 51instructs 52.Nm 53to not generate them in batch, but one at a time. 54.It Fl r 55This option controls creation of random UUID (version 4). 56.It Fl n 57This option controls the number of identifiers generated. 58By default, multiple identifiers are generated in batch. 59The upper hard limit is 2048 60.Po see 61.Xr uuidgen 2 62.Pc . 63.It Fl o 64Redirect output to 65.Ar filename 66instead of stdout. 67.El 68.Pp 69Batched generation yields a dense set of identifiers in such a way that there 70is no identifier that is larger than the smallest identifier in the set and 71smaller than the largest identifier in the set and that is not already in the 72set. 73.Pp 74When generating the identifiers one at a time, the identifiers will be close 75to each other, but operating system latency and processing time will be 76reflected in the distance between two successive identifiers. 77.Sh EXIT STATUS 78.Ex -std 79.Sh SEE ALSO 80.Xr uuidgen 2 , 81.Xr uuid 3 82.Sh HISTORY 83The 84.Nm 85command first appeared in 86.Fx 5.0 . 87