.\" Copyright (c) 2016 Andriy Gapon
.\" All rights reserved.
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.\" $FreeBSD$
.\"
.Dd October 12, 2016
.Dt ZFSBOOTCFG 8
.Os
.Sh NAME
.Nm zfsbootcfg
.Nd "specify zfsboot options for the next boot"
.Sh SYNOPSIS
.Nm
.Ao Ar options Ac
.Sh DESCRIPTION
.Nm
is used to set
.Xr boot.config 5 Ns -style
options to be used by
.Xr zfsboot 8
or
.Xr gptzfsboot 8
the next time the machine is booted.
Once
.Xr zfsboot 8
or
.Xr gptzfsboot 8
reads the information, it is deleted.
If booting fails, the machine automatically reverts to the previous
boot configuration.
The information is stored in a special reserved area of a ZFS pool.
.Xr zfsboot 8
or
.Xr gptzfsboot 8
read the boot option information from the first disk found in the first
ZFS pool found.
.Sh ENVIRONMENT
.Bl -tag -width vfs.zfs.boot.primary_pool -compact
.It Ev vfs.zfs.boot.primary_pool
The
.Xr kenv 1
variable that identifies a pool for which the options are written.
.It Ev vfs.zfs.boot.primary_vdev
The
.Xr kenv 1
variable that identifies a disk within the pool where the options
are written.
.El
.Sh EXAMPLES
Try to boot to a new
.Em boot environment
without changing the
.Cm bootfs
property of a pool:
.Pp
.Dl "zfsbootcfg ""zfs:tank/ROOT/newbe:""
.Pp
To clear the boot options:
.Pp
.Dl "zfsbootcfg """"
.Sh SEE ALSO
.Xr boot.config 5 ,
.Xr gptzfsboot 8 ,
.Xr zfsboot 8
.Sh HISTORY
.Nm
appeared in
.Fx 12.0 .
.Sh AUTHORS
This manual page was written by
.An Andriy Gapon Aq Mt avg@FreeBSD.org .
.Sh CAVEATS
At the moment,
.Nm
uses the
.Ev vfs.zfs.boot.primary_pool
and
.Ev vfs.zfs.boot.primary_vdev
.Xr kenv 1
variables to determine a ZFS pool and a disk in it where the options
are to be stored.
The variables are set by the ZFS boot chain, so there is an assumption
that the same boot disk is going to be used for the next reboot.
There is no
.Nm
option to specify a different pool or a different disk.
.Pp
.Nm
should be extended to install new
.Xr zfsboot 8
blocks in a ZFS pool.