.\" SPDX-License-Identifier: CDDL-1.0
.\"
.\" This file and its contents are supplied under the terms of the
.\" Common Development and Distribution License ("CDDL"), version 1.0.
.\" You may only use this file in accordance with the terms of version
.\" 1.0 of the CDDL.
.\"
.\" A full copy of the text of the CDDL should have accompanied this
.\" source.  A copy of the CDDL is also available via the Internet at
.\" https://opensource.org/license/CDDL-1.0.
.\"
.\" Copyright (c) 2017 by Lawrence Livermore National Security, LLC.
.\"
.Dd July 11, 2022
.Dt ZGENHOSTID 8
.Os
.
.Sh NAME
.Nm zgenhostid
.Nd generate host ID into /etc/hostid
.Sh SYNOPSIS
.Nm
.Op Fl f
.Op Fl o Ar filename
.Op Ar hostid
.
.Sh DESCRIPTION
Creates
.Pa /etc/hostid
file and stores the host ID in it.
If
.Ar hostid
was provided, validate and store that value.
Otherwise, randomly generate an ID.
.
.Sh OPTIONS
.Bl -tag -width "-o filename"
.It Fl h
Display a summary of the command-line options.
.It Fl f
Allow output overwrite.
.It Fl o Ar filename
Write to
.Pa filename
instead of the default
.Pa /etc/hostid .
.It Ar hostid
Specifies the value to be placed in
.Pa /etc/hostid .
It should be a number with a value between 1 and 2^32-1.
If
.Sy 0 ,
generate a random ID.
This value
.Em must
be unique among your systems.
It
.Em must
be an 8-digit-long hexadecimal number, optionally prefixed by
.Qq 0x .
.El
.
.Sh FILES
.Pa /etc/hostid
.
.Sh EXAMPLES
.Bl -tag -width Bd
.It Generate a random hostid and store it
.Dl # Nm
.It Record the libc-generated hostid in Pa /etc/hostid
.Dl # Nm Qq $ Ns Pq Nm hostid
.It Record a custom hostid Po Ar 0xdeadbeef Pc in Pa /etc/hostid
.Dl # Nm Ar deadbeef
.It Record a custom hostid Po Ar 0x01234567 Pc in Pa /tmp/hostid No and overwrite the file if it exists
.Dl # Nm Fl f o Ar /tmp/hostid 0x01234567
.El
.
.Sh SEE ALSO
.Xr genhostid 1 ,
.Xr hostid 1 ,
.Xr sethostid 3 ,
.Xr spl 4
.
.Sh HISTORY
.Nm
emulates the
.Xr genhostid 1
utility and is provided for use on systems which
do not include the utility or do not provide the
.Xr sethostid 3
function.