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fa30d9ed75
libbe currently only provides an API to create a recursive boot environment, without any formal support for intentionally limiting the depth. This changeset adds an API, be_create_depth, that may be used to arbitrarily restrict the depth of the new BE. Submitted by: Rob Fairbanks <rob.fx907 gmail com> MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D18564
518 lines
13 KiB
Groff
518 lines
13 KiB
Groff
.\"
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.\" SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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.\"
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.\" Copyright (c) 2017 Kyle Kneitinger
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.\" All rights reserved.
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.\" Copyright (c) 2018 Kyle Evans <kevans@FreeBSD.org>
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd April 22, 2019
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.Dt LIBBE 3
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.Os
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.Sh NAME
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.Nm libbe
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.Nd library for creating, destroying and modifying ZFS boot environments
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.Sh LIBRARY
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.Lb libbe
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.Sh SYNOPSIS
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.In be.h
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.Ft "libbe_handle_t *hdl" Ns
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.Fn libbe_init "const char *be_root"
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.Pp
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.Ft void
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.Fn libbe_close "libbe_handle_t *hdl"
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.Pp
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.Ft const char * Ns
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.Fn be_active_name "libbe_handle_t *hdl"
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.Pp
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.Ft const char * Ns
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.Fn be_active_path "libbe_handle_t *hdl"
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.Pp
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.Ft const char * Ns
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.Fn be_nextboot_name "libbe_handle_t *hdl"
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.Pp
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.Ft const char * Ns
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.Fn be_nextboot_path "libbe_handle_t *hdl"
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.Pp
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.Ft const char * Ns
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.Fn be_root_path "libbe_handle_t *hdl"
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.Pp
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.Ft int
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.Fn be_create "libbe_handle_t *hdl" "const char *be_name"
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.Pp
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.Ft int
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.Fn be_create_depth "libbe_handle_t *hdl" "const char *be_name" "const char *snap" "int depth"
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.Pp
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.Ft int
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.Fn be_create_from_existing "libbe_handle_t *hdl" "const char *be_name" "const char *be_origin"
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.Pp
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.Ft int
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.Fn be_create_from_existing_snap "libbe_handle_t *hdl" "const char *be_name" "const char *snap"
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.Pp
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.Ft int
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.Fn be_rename "libbe_handle_t *hdl" "const char *be_old" "const char *be_new"
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.Pp
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.Ft int
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.Fn be_activate "libbe_handle_t *hdl" "const char *be_name" "bool temporary"
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.Ft int
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.Fn be_destroy "libbe_handle_t *hdl" "const char *be_name" "int options"
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.Pp
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.Ft void
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.Fn be_nicenum "uint64_t num" "char *buf" "size_t bufsz"
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.Pp
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.\" TODO: Write up of mount options
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.\" typedef enum {
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.\" BE_MNT_FORCE = 1 << 0,
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.\" BE_MNT_DEEP = 1 << 1,
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.\" } be_mount_opt_t
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.Ft int
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.Fn be_mount "libbe_handle_t *hdl" "char *be_name" "char *mntpoint" "int flags" "char *result"
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.Pp
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.Ft int
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.Fn be_mounted_at "libbe_handle_t *hdl" "const char *path" "nvlist_t *details"
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.Pp
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.Ft int
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.Fn be_unmount "libbe_handle_t *hdl" "char *be_name" "int flags"
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.Pp
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.Ft int
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.Fn libbe_errno "libbe_handle_t *hdl"
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.Pp
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.Ft const char * Ns
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.Fn libbe_error_description "libbe_handle_t *hdl"
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.Pp
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.Ft void
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.Fn libbe_print_on_error "libbe_handle_t *hdl" "bool doprint"
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.Pp
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.Ft int
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.Fn be_root_concat "libbe_handle_t *hdl" "const char *be_name" "char *result"
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.Pp
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.Ft int
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.Fn be_validate_name "libbe_handle_t *hdl" "const char *be_name"
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.Pp
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.Ft int
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.Fn be_validate_snap "libbe_handle_t *hdl" "const char *snap"
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.Pp
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.Ft int
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.Fn be_exists "libbe_handle_t *hdl" "char *be_name"
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.Pp
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.Ft int
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.Fn be_export "libbe_handle_t *hdl" "const char *be_name" "int fd"
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.Pp
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.Ft int
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.Fn be_import "libbe_handle_t *hdl" "const char *be_name" "int fd"
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.Pp
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.Ft int
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.Fn be_prop_list_alloc "nvlist_t **prop_list"
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.Pp
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.Ft int
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.Fn be_get_bootenv_props "libbe_handle_t *hdl" "nvlist_t *be_list"
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.Pp
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.Ft int
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.Fn be_get_dataset_props "libbe_handle_t *hdl" "const char *ds_name" "nvlist_t *props"
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.Pp
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.Ft int
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.Fn be_get_dataset_snapshots "libbe_handle_t *hdl" "const char *ds_name" "nvlist_t *snap_list"
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.Pp
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.Ft void
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.Fn be_prop_list_free "nvlist_t *prop_list"
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.Sh DESCRIPTION
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.Nm
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interfaces with libzfs to provide a set of functions for various operations
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regarding ZFS boot environments including "deep" boot environments in which
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a boot environments has child datasets.
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.Pp
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A context structure is passed to each function, allowing for a small amount
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of state to be retained, such as errors from previous operations.
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.Nm
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may be configured to print the corresponding error message to
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.Dv stderr
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when an error is encountered with
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.Fn libbe_print_on_error .
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.Pp
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All functions returning an
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.Vt int
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return 0 on success, or a
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.Nm
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errno otherwise as described in
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.Sx DIAGNOSTICS .
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.Pp
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The
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.Fn libbe_init
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function takes an optional BE root and initializes
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.Nm ,
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returning a
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.Vt "libbe_handle_t *"
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on success, or
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.Dv NULL
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on error.
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If a BE root is supplied,
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.Nm
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will only operate out of that pool and BE root.
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An error may occur if:
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.Bl -column
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.It /boot and / are not on the same filesystem and device,
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.It libzfs fails to initialize,
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.It The system has not been properly booted with a ZFS boot
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environment,
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.It Nm
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fails to open the zpool the active boot environment resides on, or
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.It Nm
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fails to locate the boot environment that is currently mounted.
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.El
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.Pp
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The
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.Fn libbe_close
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function frees all resources previously acquired in
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.Fn libbe_init ,
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invalidating the handle in the process.
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.Pp
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The
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.Fn be_active_name
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function returns the name of the currently booted boot environment.
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This boot environment may not belong to the same BE root as the root libbe
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is operating on!
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.Pp
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The
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.Fn be_active_path
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function returns the full path of the currently booted boot environment.
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This boot environment may not belong to the same BE root as the root libbe
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is operating on!
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.Pp
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The
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.Fn be_nextboot_name
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function returns the name of the boot environment that will be active on reboot.
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.Pp
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The
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.Fn be_nextboot_path
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function returns the full path of the boot environment that will be
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active on reboot.
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.Pp
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The
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.Fn be_root_path
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function returns the boot environment root path.
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.Pp
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The
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.Fn be_create
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function creates a boot environment with the given name.
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The new boot environment will be created from a recursive snapshot of the
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currently booted boot environment.
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.Pp
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The
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.Fn be_create_depth
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function creates a boot environment with the given name from an existing
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snapshot.
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The depth parameter specifies the depth of recursion that will be cloned from
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the existing snapshot.
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A depth of '0' is no recursion and '-1' is unlimited (i.e., a recursive boot
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environment).
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.Pp
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The
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.Fn be_create_from_existing
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function creates a boot environment with the given name from the name of an
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existing boot environment.
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A recursive snapshot will be made of the origin boot environment, and the new
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boot environment will be created from that.
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.Pp
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The
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.Fn be_create_from_existing_snap
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function creates a recursive boot environment with the given name from an
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existing snapshot.
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.Pp
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The
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.Fn be_rename
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function renames a boot environment without unmounting it, as if renamed with
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the
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.Fl u
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argument were passed to
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.Nm zfs
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.Cm rename
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.Pp
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The
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.Fn be_activate
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function makes a boot environment active on the next boot.
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If the
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.Fa temporary
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flag is set, then it will be active for the next boot only, as done by
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.Xr zfsbootcfg 8 .
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Next boot functionality is currently only available when booting in x86 BIOS
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mode.
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.Pp
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The
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.Fn be_destroy
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function will recursively destroy the given boot environment.
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It will not destroy a mounted boot environment unless the
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.Dv BE_DESTROY_FORCE
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option is set in
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.Fa options .
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If the
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.Dv BE_DESTROY_ORIGIN
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option is set in
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.Fa options ,
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the
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.Fn be_destroy
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function will destroy the origin snapshot to this boot environment as well.
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.Pp
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The
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.Fn be_nicenum
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function will format
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.Fa name
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in a traditional ZFS humanized format, similar to
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.Xr humanize_number 3 .
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This function effectively proxies
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.Fn zfs_nicenum
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from libzfs.
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.Pp
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The
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.Fn be_mount
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function will mount the given boot environment.
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If
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.Fa mountpoint
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is
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.Dv NULL ,
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a mount point will be generated in
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.Pa /tmp
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using
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.Xr mkdtemp 3 .
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If
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.Fa result
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is not
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.Dv NULL ,
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it should be large enough to accommodate
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.Dv BE_MAXPATHLEN
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including the null terminator.
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the final mount point will be copied into it.
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Setting the
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.Dv BE_MNT_FORCE
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flag will pass
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.Dv MNT_FORCE
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to the underlying
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.Xr mount 2
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call.
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.Pp
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The
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.Fn be_mounted_at
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function will check if there is a boot environment mounted at the given
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.Fa path .
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If
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.Fa details
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is not
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.Dv NULL ,
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it will be populated with a list of the mounted dataset's properties.
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This list of properties matches the properties collected by
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.Fn be_get_bootenv_props .
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.Pp
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The
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.Fn be_unmount
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function will unmount the given boot environment.
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Setting the
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.Dv BE_MNT_FORCE
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flag will pass
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.Dv MNT_FORCE
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to the underlying
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.Xr mount 2
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call.
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.Pp
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The
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.Fn libbe_errno
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function returns the
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.Nm
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errno.
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.Pp
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The
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.Fn libbe_error_description
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function returns a string description of the currently set
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.Nm
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errno.
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.Pp
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The
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.Fn libbe_print_on_error
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function will change whether or not
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.Nm
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prints the description of any encountered error to
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.Dv stderr ,
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based on
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.Fa doprint .
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.Pp
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The
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.Fn be_root_concat
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function will concatenate the boot environment root and the given boot
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environment name into
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.Fa result .
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.Pp
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The
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.Fn be_validate_name
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function will validate the given boot environment name for both length
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restrictions as well as valid character restrictions.
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This function does not set the internal library error state.
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.Pp
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The
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.Fn be_validate_snap
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function will validate the given snapshot name.
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The snapshot must have a valid name, exist, and have a mountpoint of
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.Pa / .
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This function does not set the internal library error state.
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.Pp
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The
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.Fn be_exists
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function will check whether the given boot environment exists and has a
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mountpoint of
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.Pa / .
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This function does not set the internal library error state, but will return
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the appropriate error.
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.Pp
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The
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.Fn be_export
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function will export the given boot environment to the file specified by
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.Fa fd .
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A snapshot will be created of the boot environment prior to export.
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.Pp
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The
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.Fn be_import
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function will import the boot environment in the file specified by
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.Fa fd ,
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and give it the name
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.Fa be_name .
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.Pp
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The
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.Fn be_prop_list_alloc
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function allocates a property list suitable for passing to
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.Fn be_get_bootenv_props ,
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.Fn be_get_dataset_props ,
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or
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.Fn be_get_dataset_snapshots .
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It should be freed later by
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.Fa be_prop_list_free .
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.Pp
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The
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.Fn be_get_bootenv_props
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function will populate
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.Fa be_list
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with
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.Vt nvpair_t
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of boot environment names paired with an
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.Vt nvlist_t
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of their properties.
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The following properties are currently collected as appropriate:
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.Bl -column "Returned name"
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.It Sy Returned name Ta Sy Description
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.It dataset Ta -
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.It name Ta Boot environment name
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.It mounted Ta Current mount point
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.It mountpoint Ta Do mountpoint Dc property
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.It origin Ta Do origin Dc property
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.It creation Ta Do creation Dc property
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.It active Ta Currently booted environment
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.It used Ta Literal Do used Dc property
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.It usedds Ta Literal Do usedds Dc property
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.It usedsnap Ta Literal Do usedrefreserv Dc property
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.It referenced Ta Literal Do referenced Dc property
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.It nextboot Ta Active on next boot
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.El
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.Pp
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Only the
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.Dq dataset ,
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.Dq name ,
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.Dq active ,
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and
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.Dq nextboot
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returned values will always be present.
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All other properties may be omitted if not available.
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.Pp
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The
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.Fn be_get_dataset_props
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function will get properties of the specified dataset.
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.Fa props
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is populated directly with a list of the properties as returned by
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.Fn be_get_bootenv_props .
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.Pp
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The
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.Fn be_get_dataset_snapshots
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function will retrieve all snapshots of the given dataset.
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.Fa snap_list
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will be populated with a list of
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.Vt nvpair_t
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exactly as specified by
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.Fn be_get_bootenv_props .
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.Pp
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The
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.Fn be_prop_list_free
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function will free the property list.
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.Sh DIAGNOSTICS
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Upon error, one of the following values will be returned:
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.Bl -dash -offset indent -compact
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.It
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BE_ERR_SUCCESS
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.It
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BE_ERR_INVALIDNAME
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.It
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BE_ERR_EXISTS
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.It
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BE_ERR_NOENT
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.It
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BE_ERR_PERMS
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.It
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BE_ERR_DESTROYACT
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.It
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BE_ERR_DESTROYMNT
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.It
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BE_ERR_BADPATH
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.It
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BE_ERR_PATHBUSY
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.It
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BE_ERR_PATHLEN
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.It
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BE_ERR_BADMOUNT
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.It
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BE_ERR_NOORIGIN
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.It
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BE_ERR_MOUNTED
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.It
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BE_ERR_NOMOUNT
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.It
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BE_ERR_ZFSOPEN
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.It
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BE_ERR_ZFSCLONE
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.It
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BE_ERR_IO
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.It
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BE_ERR_NOPOOL
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.It
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BE_ERR_NOMEM
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.It
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BE_ERR_UNKNOWN
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.It
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BE_ERR_INVORIGIN
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.El
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.Sh SEE ALSO
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.Xr bectl 8
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.Sh HISTORY
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.Nm
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and its corresponding command,
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.Xr bectl 8 ,
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were written as a 2017 Google Summer of Code project with Allan Jude serving
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as a mentor.
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Later work was done by
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.An Kyle Evans Aq Mt kevans@FreeBSD.org .
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