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.Dd September 13, 2020
.Dt ZGENHOSTID 8 SMM
.Os Linux
.Sh NAME
.Nm zgenhostid
.Nd generate and store a hostid in
.Em /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 hostid in it.
If the user provides
.Op Ar hostid
on the command line, validates and stores that value.
Otherwise, randomly generates a value to store.
.Bl -tag -width "hostid"
.It Fl h
Display a summary of the command-line options.
.It Fl f
Force file overwrite.
.It Fl o Ar filename
Write to
.Pa filename
instead of default
.Pa /etc/hostd
.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 it is 0, zgenhostid will generate a random hostid.
This value
.Sy must
be unique among your systems.
It
.Sy must
be expressed in hexadecimal and be exactly
.Em 8
digits long, optionally prefixed by
.Em 0x .
.El
.Sh FILES
.Pa /etc/hostid
.Sh EXAMPLES
.Bl -tag -width Bd
.It Generate a random hostid and store it
.Bd -literal
# zgenhostid
.Ed
.It Record the libc-generated hostid in Pa /etc/hostid
.Bd -literal
# zgenhostid "$(hostid)"
.Ed
.It Record a custom hostid (0xdeadbeef) in Pa /etc/hostid
.Bd -literal
# zgenhostid deadbeef
.Ed
.It Record a custom hostid (0x01234567) in Pa /tmp/hostid
and ovewrite the file if it exists
.Bd -literal
# zgenhostid -f -o /tmp/hostid 0x01234567
.Ed
.El
.Sh SEE ALSO
.Xr genhostid 1 ,
.Xr hostid 1 ,
.Xr sethostid 3 ,
.Xr spl-module-parameters 5
.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
.Xr sethostid 3
call.