xref: /freebsd/bin/uuidgen/uuidgen.1 (revision 6e74b603fc021761c0a20e08f58b674f45ad5f04)

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.Dd March 1, 2023
.Dt UUIDGEN 1
.Os
.Sh NAME
.Nm uuidgen
.Nd generate universally unique identifiers
.Sh SYNOPSIS
.Nm
.Op Fl 1
.Op Fl r
.Op Fl c
.Op Fl n Ar count
.Op Fl o Ar filename
.Sh DESCRIPTION
The
.Nm
utility by default generates a single DCE version 1
universally unique identifier (UUID),
also known as a globally unique identifier (GUID).
The UUID is written to stdout by default.
The following options can be used to change the behaviour of
.Nm :
.Bl -tag -width indent
.It Fl 1
This option only has effect if multiple identifiers are to be generated and
instructs
.Nm
to not generate them in batch, but one at a time.
.It Fl r
This option controls creation of random UUID (version 4).
.It Fl c
This option controls creation of compact UUID (without hyphen).
.It Fl n
This option controls the number of identifiers generated.
By default, multiple identifiers are generated in batch.
The upper hard limit is 2048
.Po see
.Xr uuidgen 2
.Pc .
.It Fl o
Redirect output to
.Ar filename
instead of stdout.
.El
.Pp
Batched generation yields a dense set of identifiers in such a way that there
is no identifier that is larger than the smallest identifier in the set and
smaller than the largest identifier in the set and that is not already in the
set.
.Pp
When generating the identifiers one at a time, the identifiers will be close
to each other, but operating system latency and processing time will be
reflected in the distance between two successive identifiers.
.Sh EXIT STATUS
.Ex -std
.Sh EXAMPLES
Generate a batch of three UUIDs.
Notice the similarity of the string before the first hyphen of the UUID
(known as
.Em time_low
in
.Em rfc4122
):
.Bd -literal -offset indent
$ uuidgen -n3
8bc44345-4d90-11ee-88c7-b42e991fc52e
8bc44346-4d90-11ee-88c7-b42e991fc52e
8bc44347-4d90-11ee-88c7-b42e991fc52e
.Ed
.Pp
Generate a batch of random UUIDs without hyphens:
.Bd -literal -offset indent
$ uuidgen -r -c -n3
5ad8b60a0f4e41f59c82d273202275f9
6c41925486cd4bf59720a5bad85de2e4
8144fdab63f648a1812d12453f975313
.Ed
.Pp
Notice that the UUIDs are not similar to each other.
.Sh SEE ALSO
.Xr uuidgen 2 ,
.Xr uuid 3
.Sh HISTORY
The
.Nm
command first appeared in
.Fx 5.0 .