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zsnapshots: recovery environment helper tool
In the event that no boot environments with a valid /boot are found, recovery might be as simple as interacting with an older snapshot. The recovery shell tool `zsnapshots` attempts to make that easier by allowing access to the main snapshot interface for a given dataset. fzf defaults suitable for the main interfaces were moved to a lib file that can be sourced. These defaults allow smaller tools to match the same behavior that fzf has when invoked from /bin/zfsbootmenu . select_kernel now returns 1 when the 'kernels' file for a boot environment can't be found, with nothing printed. The caller is expected to handle that condition accordingly. Fixes #418
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‎docs/online/recovery-shell.rst

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@@ -16,6 +16,10 @@ Common Commands
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Directly *kexec* a kernel and initramfs from a boot environment, allowing any kernel and initramfs to be loaded into memory and immediately booted.
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**zsnapshots** *dataset*
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Access the snapshot browser for a dataset, allowing cloning and rollback operations to be initiated.
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**zreport**
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List ZFS module, pool and dataset details for bug reports.

‎releng/rst2help.sh

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@@ -1,4 +1,6 @@
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#!/bin/bash
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# vim: softtabstop=2 shiftwidth=2 expandtab
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set -e
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td="zfsbootmenu/help-files"
@@ -7,7 +9,8 @@ for size in 52 92 132 ; do
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for doc in docs/online/*.rst docs/man/zfsbootmenu.7.rst; do
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[ -d "${td}/${size}" ] || mkdir -p "${td}/${size}"
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file="$( basename -s .rst "${doc}" ).ansi"
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echo "Converting ${doc}"
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echo "Converting ${doc} for ${size} columns"
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#shellcheck disable=SC2016
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COLUMNS="${size}" rst2ansi <(sed -E 's/:(doc|manpage):`([^<`]+)( <[^>]+>)?`/`\2`/g' "${doc}") | \
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sed '1s/ - \(.*\)$/\n\n\o033\[1m\1\o033\[0m/;s/\[3m/\[33m/g' > "${td}/${size}/${file}"
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done

‎zfsbootmenu/bin/zfsbootmenu

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@@ -9,6 +9,7 @@ sources=(
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/lib/zfsbootmenu-lib.sh
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/lib/kmsg-log-lib.sh
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/etc/profile
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/lib/fzf-defaults.sh
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)
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for src in "${sources[@]}"; do
@@ -76,48 +77,6 @@ if [ -d /libexec/setup.d ]; then
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unset _hook
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fi
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# Override control_term if executing over SSH
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# shellcheck disable=SC2034
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[ -n "${SSH_TTY}" ] && control_term="${SSH_TTY}"
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# Single quote the help binds so that $HELP_SECTION expands when the key combo
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# is pressed, and not now.
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# Double quote the zlogtail lines so that they expand immediately
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# shellcheck disable=SC2016
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fuzzy_default_options=(
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"--ansi" "--no-clear" "--cycle" "--color=16"
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"--layout=reverse-list" "--inline-info" "--tac"
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"--bind" '"alt-h:execute[ /libexec/zfsbootmenu-help -L ${HELP_SECTION:-main-screen} ]"'
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"--bind" '"ctrl-h:execute[ /libexec/zfsbootmenu-help -L ${HELP_SECTION:-main-screen} ]"'
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"--bind" '"ctrl-alt-h:execute[ /libexec/zfsbootmenu-help -L ${HELP_SECTION:-main-screen} ]"'
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"--bind" "\"alt-l:execute[ /bin/zlogtail ]${HAS_REFRESH:++refresh-preview}\""
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"--bind" "\"ctrl-l:execute[ /bin/zlogtail ]${HAS_REFRESH:++refresh-preview}\""
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"--bind" "\"ctrl-alt-l:execute[ /bin/zlogtail ]${HAS_REFRESH:++refresh-preview}\""
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)
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if [ -n "${HAS_BORDER}" ]; then
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# shellcheck disable=SC2016
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fuzzy_default_options+=(
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"--border-label-pos=top" "--border=top"
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"--color=border:white" "--separator=''"
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)
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fi
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# shellcheck disable=SC2016,SC2086
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if [ ${loglevel:-4} -eq 7 ] ; then
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fuzzy_default_options+=(
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"--bind" '"alt-t:execute[ /sbin/ztrace > ${control_term} ]"'
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"--bind" '"ctrl-t:execute[ /sbin/ztrace > ${control_term} ]"'
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"--bind" '"ctrl-alt-t:execute[ /sbin/ztrace > ${control_term} ]"'
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"--bind" '"f12:execute[ /libexec/zfunc emergency_shell \"debugging shell\" > ${control_term} ]"'
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)
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fi
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export FUZZYSEL=fzf
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export PREVIEW_HEIGHT=2
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export FZF_DEFAULT_OPTS="${fuzzy_default_options[*]}"
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# Clear screen before a possible password prompt
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tput clear
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‎zfsbootmenu/bin/zsnapshots

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@@ -0,0 +1,53 @@
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#!/bin/bash
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sources=(
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/lib/profiling-lib.sh
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/etc/zfsbootmenu.conf
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/lib/kmsg-log-lib.sh
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/lib/zfsbootmenu-core.sh
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/lib/zfsbootmenu-lib.sh
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/lib/fzf-defaults.sh
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)
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for src in "${sources[@]}"; do
13+
# shellcheck disable=SC1090
14+
if ! source "${src}" >/dev/null 2>&1 ; then
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echo -e "\033[0;31mWARNING: ${src} was not sourced; unable to proceed\033[0m"
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exit
17+
fi
18+
done
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20+
# Replace the global_header function with a stub
21+
global_header() {
22+
echo -n -e "\\033[1;33m[ Recover from snapshot ]"
23+
}
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25+
if [ $# -ne 1 ] ; then
26+
echo "Usage: $0 filesystem"
27+
exit
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fi
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30+
fs="${1}"
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COLUMNS="$( tput cols )"
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34+
while true; do
35+
if ! selection="$( draw_snapshots "${fs}" )" ; then
36+
tput clear
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exit
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fi
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40+
# shellcheck disable=SC2162
41+
IFS=, read subkey selected_snap <<< "${selection}"
42+
selected_snap="${selected_snap%,*}"
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case "${subkey}" in
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"left"|"right")
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continue
47+
;;
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esac
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if is_snapshot "${selected_snap}" ; then
51+
snapshot_dispatcher "${selected_snap}" "${subkey}"
52+
fi
53+
done

‎zfsbootmenu/help-files/132/recovery-shell.ansi

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@@ -16,6 +16,10 @@
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Directly kexec a kernel and initramfs from a boot environment, allowing any kernel and initramfs to be loaded into memory and
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immediately booted.
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zsnapshots dataset
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Access the snapshot browser for a dataset, allowing cloning and rollback operations to be initiated.
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zreport
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List ZFS module, pool and dataset details for bug reports.

‎zfsbootmenu/help-files/52/recovery-shell.ansi

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@@ -20,6 +20,12 @@
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initramfs to be loaded into memory and
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immediately booted.
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zsnapshots dataset
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Access the snapshot browser for a dataset,
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allowing cloning and rollback operations to
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be initiated.
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zreport
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List ZFS module, pool and dataset details for

‎zfsbootmenu/help-files/92/recovery-shell.ansi

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@@ -16,6 +16,11 @@
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Directly kexec a kernel and initramfs from a boot environment, allowing any kernel and
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initramfs to be loaded into memory and immediately booted.
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zsnapshots dataset
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Access the snapshot browser for a dataset, allowing cloning and rollback operations to
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be initiated.
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zreport
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List ZFS module, pool and dataset details for bug reports.

‎zfsbootmenu/lib/fzf-defaults.sh

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#!/bin/bash
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# vim: softtabstop=2 shiftwidth=2 expandtab
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# Override control_term if executing over SSH
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# shellcheck disable=SC2034
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[ -n "${SSH_TTY}" ] && control_term="${SSH_TTY}"
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# shellcheck disable=SC2016
9+
fuzzy_default_options=(
10+
"--ansi" "--no-clear" "--cycle" "--color=16"
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"--layout=reverse-list" "--inline-info" "--tac"
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"--bind" '"alt-h:execute[ /libexec/zfsbootmenu-help -L ${HELP_SECTION:-main-screen} ]"'
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"--bind" '"ctrl-h:execute[ /libexec/zfsbootmenu-help -L ${HELP_SECTION:-main-screen} ]"'
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"--bind" '"ctrl-alt-h:execute[ /libexec/zfsbootmenu-help -L ${HELP_SECTION:-main-screen} ]"'
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"--bind" "\"alt-l:execute[ /bin/zlogtail ]${HAS_REFRESH:++refresh-preview}\""
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"--bind" "\"ctrl-l:execute[ /bin/zlogtail ]${HAS_REFRESH:++refresh-preview}\""
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"--bind" "\"ctrl-alt-l:execute[ /bin/zlogtail ]${HAS_REFRESH:++refresh-preview}\""
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)
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20+
if [ -n "${HAS_BORDER}" ]; then
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# shellcheck disable=SC2016
22+
fuzzy_default_options+=(
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"--border-label-pos=top" "--border=top"
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"--color=border:white" "--separator=''"
25+
)
26+
fi
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28+
# shellcheck disable=SC2016,SC2086
29+
if [ ${loglevel:-4} -eq 7 ] ; then
30+
fuzzy_default_options+=(
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"--bind" '"alt-t:execute[ /sbin/ztrace > ${control_term} ]"'
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"--bind" '"ctrl-t:execute[ /sbin/ztrace > ${control_term} ]"'
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"--bind" '"ctrl-alt-t:execute[ /sbin/ztrace > ${control_term} ]"'
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"--bind" '"f12:execute[ /libexec/zfunc emergency_shell \"debugging shell\" > ${control_term} ]"'
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)
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fi
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38+
export FUZZYSEL=fzf
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export PREVIEW_HEIGHT=2
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export FZF_DEFAULT_OPTS="${fuzzy_default_options[*]}"

‎zfsbootmenu/lib/zfsbootmenu-completions.sh

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@@ -71,6 +71,20 @@ _mount_zfs() {
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}
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complete -F _mount_zfs mount_zfs
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74+
_zsnapshots() {
75+
local ZFS
76+
COMPREPLY=()
77+
78+
[ "${#COMP_WORDS[@]}" != "2" ] && return
79+
80+
for FS in $( zfs list -H -o name ) ; do
81+
ZFS+=("${FS}")
82+
done
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84+
COMPREPLY=( $( compgen -W "${ZFS[*]}" -- "${COMP_WORDS[1]}" ) )
85+
}
86+
complete -F _zsnapshots zsnapshots
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_zkexec() {
7589
local ARG index
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COMPREPLY=()

‎zfsbootmenu/lib/zfsbootmenu-core.sh

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@@ -771,10 +771,10 @@ find_be_kernels() {
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772772
# arg1: ZFS filesystem
773773
# prints: fs kernel initramfs
774-
# returns: nothing
774+
# returns: 0 if a kernel can be identified, 1 if not
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776776
select_kernel() {
777-
local zfsbe bepath specific_kernel kexec_args spec_kexec_args
777+
local zfsbe kernel_list specific_kernel kexec_args spec_kexec_args
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779779
zfsbe="${1}"
780780
if [ -z "${zfsbe}" ]; then
@@ -783,10 +783,15 @@ select_kernel() {
783783
fi
784784
zdebug "zfsbe set to ${zfsbe}"
785785

786-
bepath="$( be_location "${zfsbe}" )"
786+
kernel_list="$( be_location "${zfsbe}" )/kernels"
787+
788+
if [ ! -f "${kernel_list}" ]; then
789+
zerror "kernel list '${kernel_list}' missing"
790+
return 1
791+
fi
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788793
# By default, select the last kernel entry
789-
kexec_args="$( tail -1 "${bepath}/kernels" )"
794+
kexec_args="$( tail -1 "${kernel_list}" )"
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791796
# If a specific kernel is listed, prefer it when possible
792797
specific_kernel="$( zfs get -H -o value org.zfsbootmenu:kernel "${zfsbe}" )"
@@ -800,7 +805,7 @@ select_kernel() {
800805
kexec_args="${spec_kexec_args}"
801806
break
802807
fi
803-
done <<<"$( tac "${bepath}/kernels" )"
808+
done <<<"$( tac "${kernel_list}" )"
804809
fi
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806811
zdebug "using kexec args: ${kexec_args}"

‎zfsbootmenu/libexec/zfsbootmenu-preview

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@@ -11,7 +11,7 @@ ENV="${1}"
1111
BOOTFS="${2}"
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1313
# shellcheck disable=SC2034
14-
IFS=' ' read -r _fs selected_kernel _initramfs <<<"$( select_kernel "${ENV}")"
14+
IFS=' ' read -r _fs selected_kernel _initramfs <<<"$( select_kernel "${ENV}" || echo "- missing -" )"
1515
selected_kernel="${selected_kernel##*/}"
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1717
if [ "${BOOTFS}" = "${ENV}" ]; then

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