1.\" 2.\" SPDX-License-Identifier: BSD-2-Clause 3.\" 4.\" Copyright (c) 2002 Marcel Moolenaar 5.\" All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 16.\" 17.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27.\" 28.Dd August 27, 2025 29.Dt UUIDGEN 1 30.Os 31.Sh NAME 32.Nm uuidgen 33.Nd generate universally unique identifiers 34.Sh SYNOPSIS 35.Nm 36.Op Fl 1cr 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 c 55This option controls creation of compact UUID (without hyphen). 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.It Fl r 68This option controls creation of random UUID (version 4). 69.El 70.Pp 71Batched generation yields a dense set of identifiers in such a way that there 72is no identifier that is larger than the smallest identifier in the set and 73smaller than the largest identifier in the set and that is not already in the 74set. 75.Pp 76When generating the identifiers one at a time, the identifiers will be close 77to each other, but operating system latency and processing time will be 78reflected in the distance between two successive identifiers. 79.Sh EXIT STATUS 80.Ex -std 81.Sh EXAMPLES 82Generate a batch of three UUIDs. 83Notice the similarity of the string before the first hyphen of the UUID 84.Po known as 85.Em time_low 86in 87.Em rfc4122 88.Pc : 89.Bd -literal -offset indent 90$ uuidgen -n3 918bc44345-4d90-11ee-88c7-b42e991fc52e 928bc44346-4d90-11ee-88c7-b42e991fc52e 938bc44347-4d90-11ee-88c7-b42e991fc52e 94.Ed 95.Pp 96Generate a batch of random UUIDs without hyphens: 97.Bd -literal -offset indent 98$ uuidgen -r -c -n3 995ad8b60a0f4e41f59c82d273202275f9 1006c41925486cd4bf59720a5bad85de2e4 1018144fdab63f648a1812d12453f975313 102.Ed 103.Pp 104Notice that the UUIDs are not similar to each other. 105.Sh SEE ALSO 106.Xr uuidgen 2 , 107.Xr uuid 3 108.Sh HISTORY 109The 110.Nm 111command first appeared in 112.Fx 5.0 . 113