Correct typo

* Update Description section:
Adds experimental method for booting to a snapshot in read-only mode with systemd.

* Update Installation section:
Adds : Run make help to check what options are available.
Adds new dependency: strings

41_snapshots-btrfs

@@ -1,38 +1,33 @@
 #! /usr/bin/env bash
 #
-#
 # Written by: Antynea
 # BTC donation address: 1Lbvz244WA8xbpHek9W2Y12cakM6rDe5Rt
 # Github: https://github.com/Antynea/grub-btrfs
 #
 # Purpose:
 #   Improves Grub by adding "btrfs snapshots" to the Grub menu.
-#   You can start your system on a "snapshot" from the Grub menu.
+#   You can boot your system on a "snapshot" from the Grub menu.
-#   Supports manual snapshots, snapper ...
+#   Supports manual snapshots, snapper, timeshift ...
-#   Warning : booting on read-only snapshots can be tricky
+#   Warning : booting on read-only snapshots can be tricky.
 #   (Read about it, https://github.com/Antynea/grub-btrfs#warning-booting-on-read-only-snapshots-can-be-tricky)
 #
 # What this script does:
 # - Automatically List snapshots existing on root partition (btrfs).
 # - Automatically Detect if "/boot" is in separate partition.
-# - Automatically Detect kernel, initramfs and intel microcode in "/boot" directory on snapshots.
+# - Automatically Detect kernel, initramfs and intel/amd microcode in "/boot" directory on snapshots.
-# - Automatically Create corresponding "menuentry" in grub.cfg
+# - Automatically Create corresponding "menuentry" in grub.cfg.
-# - Automatically detect snapper and use snapper's snapshot description if available.
+# - Automatically detect the type/tags and descriptions/comments of snapper/timeshift snapshots.
 # - Automatically generate grub.cfg if you use the provided systemd service.
 #
 # Installation:
-# - Run `make install` or look into Makefile for instructions on where to put each file.
+# - Refer to https://github.com/Antynea/grub-btrfs#installation-
 #
 # Customization:
-#  Refer to config for the list of available options and their default values.
+#  You have the possibility to modify many parameters in /etc/default/grub-btrfs/config.
-#  Place your configurations to /etc/default/grub-btrfs/config.
 #
 # Automatically update Grub
-#  If you would like Grub to automatically update when a snapshots is made or deleted:
+#  If you would like grub-btrfs menu to automatically update when a snapshot is created or deleted:
-#  - Use systemctl start/enable grub-btrfs.path
+#  - Refer to https://github.com/Antynea/grub-btrfs#automatically-update-grub.
-#  - grub-btrfs.path automatically (re)generates grub.cfg when a modification appears in /.snapshots folder (by default).
-#  - If your snapshots aren't mounted in /.snapshots, you must modify the watch folder using systemctl edit grub-btrfs.path
-#  - See https://github.com/Antynea/grub-btrfs#automatically-update-grub
 #
 # Special thanks for assistance and contributions:
 # - My friends
@@ -41,66 +36,71 @@
 
 set -e
 
-prefix="/usr"
-exec_prefix="/usr"
-datarootdir="/usr/share"
 sysconfdir="/etc"
 grub_btrfs_config="${sysconfdir}/default/grub-btrfs/config"
 
 [[ -f "$grub_btrfs_config" ]] && . "$grub_btrfs_config"
-. "$datarootdir/grub/grub-mkconfig_lib"
+[[ -f "${sysconfdir}/default/grub" ]] && . "${sysconfdir}/default/grub"
-. "${sysconfdir}/default/grub"
+
+## Exit the script, if:
+[[ "${GRUB_BTRFS_DISABLE,,}" == "true" ]] && exit 0 # Disable Grub-btrfs is set to true (default=false)
+if ! type btrfs >/dev/null 2>&1; then exit 0; fi # btrfs-progs isn't installed
+[[ -f "${GRUB_BTRFS_MKCONFIG_LIB:-/usr/share/grub/grub-mkconfig_lib}" ]] && . "${GRUB_BTRFS_MKCONFIG_LIB:-/usr/share/grub/grub-mkconfig_lib}" || exit 0 # grub-mkconfig_lib couldn't be found
+# Root filesystem isn't btrfs
+root_fs=$(${grub_probe} --target="fs" / 2>/dev/null)
+[[ "$root_fs" != "btrfs" ]] && exit 0
+
+## Error Handling
+print_error()
+{
+    local err_msg="$*"
+    local bug_report="If you think an error has occurred , please file a bug report at \" https://github.com/Antynea/grub-btrfs \""
+    printf "%s\n" "${err_msg}" "${bug_report}" >&2 ;
+    exit 0
+}
+
+printf "Detecting snapshots ...\n" >&2 ;
 
-### Variables in /etc/default/grub-btrfs/config
-## Disable Grub-btrfs (default=active)
-[[ "${GRUB_BTRFS_DISABLE:-"false"}" == "true" ]] && exit 0
 ## Submenu name
 distro=$(awk -F "=" '/^NAME=/ {gsub(/"/, "", $2); print $2}' /etc/os-release)
 submenuname=${GRUB_BTRFS_SUBMENUNAME:-"${distro:-Linux} snapshots"}
-## Prefix entry
+## Limit snapshots to show in the Grub menu (default=50)
-prefixentry=${GRUB_BTRFS_PREFIXENTRY:-"Snapshot:"}
-## Limit snapshots to show in the Grub menu
 limit_snap_show="${GRUB_BTRFS_LIMIT:-50}"
 ## How to sort snapshots list
-btrfssubvolsort=(--sort="${GRUB_BTRFS_SUBVOLUME_SORT:-"-rootid"}")
+btrfs_subvolume_sort="--sort=${GRUB_BTRFS_SUBVOLUME_SORT:-"-rootid"}"
-## Snapper's config name
-snapper_config=${GRUB_BTRFS_SNAPPER_CONFIG:-"root"}
 ## Customize GRUB directory, where "grub.cfg" file is saved
 grub_directory=${GRUB_BTRFS_GRUB_DIRNAME:-"/boot/grub"}
 ## Customize BOOT directory, where kernels/initrams/microcode is saved.
 boot_directory=${GRUB_BTRFS_BOOT_DIRNAME:-"/boot"}
 ## Password protection management for submenu
 # Protection support for submenu (--unrestricted)
-case "${GRUB_BTRFS_DISABLE_PROTECTION_SUBMENU:-"false"}" in
+case "${GRUB_BTRFS_DISABLE_PROTECTION_SUBMENU,,}" in
     true)   unrestricted_access_submenu="--unrestricted ";;
     *)      unrestricted_access_submenu=""
 esac
 # Authorized users (--users foo,bar)
-if [ ! -z "${GRUB_BTRFS_PROTECTION_AUTHORIZED_USERS}" ] ; then
+if [ -n "${GRUB_BTRFS_PROTECTION_AUTHORIZED_USERS}" ] ; then
     protection_authorized_users="--users ${GRUB_BTRFS_PROTECTION_AUTHORIZED_USERS} "
 fi
 
-### variables script
+## Probe informations of Root and Boot devices
-## Probe info "Boot partition"
+# Probe info "Root partition"
-# Boot device
+root_device=$(${grub_probe} --target=device /) # Root device
-boot_device=$(${grub_probe} --target=device ${boot_directory})
+root_uuid=$(${grub_probe} --device ${root_device} --target="fs_uuid" 2>/dev/null) # UUID of the root device
-# hints string
+root_uuid_subvolume=$(btrfs subvolume show / 2>/dev/null) || print_error "UUID of the root subvolume is not available"; # If UUID of root subvolume is not available, then exit
-boot_hs=$(${grub_probe} --device ${boot_device} --target="hints_string" 2>/dev/null)
+root_uuid_subvolume=$(awk -F":" 'match($1, /(^[ \t]+UUID)/) {sub(/^[ \t]+/, "", $2); print $2}' <<< "$root_uuid_subvolume") # UUID of the root subvolume
-# UUID of the boot partition
+# Probe info "Boot partition"
-boot_uuid=$(${grub_probe} --device ${boot_device} --target="fs_uuid" 2>/dev/null)
+boot_device=$(${grub_probe} --target=device ${boot_directory}) # Boot device
-# Type filesystem of boot partition
+boot_uuid=$(${grub_probe} --device ${boot_device} --target="fs_uuid" 2>/dev/null) # UUID of the boot device
-boot_fs=$(${grub_probe} --device ${boot_device} --target="fs" 2>/dev/null)
+boot_uuid_subvolume=$(btrfs subvolume show "$boot_directory" 2>/dev/null) || boot_uuid_subvolume=" UUID: $root_uuid_subvolume"; # If boot folder isn't a subvolume, then UUID=root_uuid_subvolume
-## Probe info "Root partition"
+boot_uuid_subvolume=$(awk -F":" 'match($1, /(^[ \t]+UUID)/) {sub(/^[ \t]+/, "", $2); print $2}' <<< "$boot_uuid_subvolume") # UUID of the boot subvolume
-# Type filesystem of root partition
+boot_hs=$(${grub_probe} --device ${boot_device} --target="hints_string" 2>/dev/null) # hints string
-root_fs=$(${grub_probe} --target="fs" / 2>/dev/null)
+boot_fs=$(${grub_probe} --device ${boot_device} --target="fs" 2>/dev/null) # Type filesystem of boot device
-# Root device
+
-root_device=$(${grub_probe} --target=device /)
-# UUID of the root partition
-root_uuid=$(${grub_probe} --device ${root_device} --target="fs_uuid" 2>/dev/null)
 ## Parameters passed to the kernel
 kernel_parameters="$GRUB_CMDLINE_LINUX $GRUB_CMDLINE_LINUX_DEFAULT"
 ## Mount point location
-gbgmp=$(mktemp -d)
+grub_btrfs_mount_point=$(mktemp -dt grub-btrfs.XXXXXXXXXX)
 ## Class for theme
 CLASS="--class snapshots --class gnu-linux --class gnu --class os"
 ## save IFS
@@ -115,62 +115,89 @@ else
     LINUX_ROOT_DEVICE=UUID=${root_uuid}
 fi
 }
-
+## Detect rootflags
-### Error Handling
+detect_rootflags()
-print_error()
 {
-    local arg="$@"
+    local fstabflags=$(grep -oE '^\s*[^#][[:graph:]]+\s+/\s+btrfs\s+[[:graph:]]+' "${grub_btrfs_mount_point}/${snap_dir_name_trim}/etc/fstab" \
-    local nothing_to_do="If you think an error has occurred , please file a bug report at \" https://github.com/Antynea/grub-btrfs \"\nNothing to do. Abort.\n"
+                        | sed -E 's/^.*[[:space:]]([[:graph:]]+)$/\1/;s/,?subvol(id)?=[^,$]+//g;s/^,//')
-    printf "${arg}\n${nothing_to_do}" >&2 ;
+    rootflags="rootflags=${fstabflags:+$fstabflags,}${GRUB_BTRFS_ROOTFLAGS:+$GRUB_BTRFS_ROOTFLAGS,}"
-    exit 0
 }
 
-test_btrfs()
+unmount_grub_btrfs_mount_point()
 {
-    [[ "$root_fs" != "btrfs" ]] && print_error "Root partition isn't a btrfs filesystem.\nThis script only supports snapshots of the btrfs filesystem."
+if [[ -d "$grub_btrfs_mount_point" ]]; then
-    set +e
+    local wait=true
-    type btrfs >/dev/null 2>&1
+    local wait_max=0
-    if [[ $? -ne 0 ]]; then
+    printf "Unmount %s .." "$grub_btrfs_mount_point" >&2;
-        print_error "Unable to retrieve info from btrfs filesystem, make sure you have btrfs-progs on your system."
+    while $wait; do
+        if grep -qs "$grub_btrfs_mount_point" /proc/mounts; then
+            wait_max=$((1+wait_max))
+            if umount "$grub_btrfs_mount_point" >/dev/null 2>&1; then
+                wait=false # umount successful
+                printf " Success\n" >&2;
+            elif [[ $wait_max = 10 ]]; then
+                printf "\nWarning: Unable to unmount %s in %s\n" "$root_device" "$grub_btrfs_mount_point" >&2;
+                break;
+            else
+                printf "." >&2 ; # output to show that the script is alive
+                sleep 2 # wait 2 seconds before retry
+            fi
+        else
+            wait=false # not mounted
+            printf " Success\n" >&2;
+        fi
+    done
+    if [[ "$wait" != true ]]; then
+        if ! rm -d "$grub_btrfs_mount_point" >/dev/null 2>&1; then
+            printf "Unable to delete %s: Device or ressource is busy\n" "$grub_btrfs_mount_point" >&2;
+        fi
     fi
-    set -e
+fi
 }
 
-### Script
 ## Create entry
 entry()
 {
-echo "$@" >> "$grub_directory/grub-btrfs.cfg"
+echo "$@" >> "$grub_directory/grub-btrfs.new"
 }
 
 ## menu entries
+old_kernel_parameters=${kernel_parameters}
 make_menu_entries()
 {
+    kernel_parameters="${old_kernel_parameters}"
+    if [[ "${GRUB_BTRFS_SYSTEMD_VOLATILE}" == true ]] ; then
+        if [[ $(strings -n7 "$grub_btrfs_mount_point/$snap_dir_name_trim/usr/bin/init" | grep -aEiom1 'upstart|systemd|sysvinit') == systemd ]] \
+           || [[ $(strings -n7 "$grub_btrfs_mount_point/$snap_dir_name_trim/sbin/init" | grep -aEiom1 'upstart|systemd|sysvinit') == systemd ]]; then
+                [[ $(btrfs property get "$grub_btrfs_mount_point/$snap_dir_name_trim" ro) != "ro=false" ]] && kernel_parameters="${kernel_parameters} systemd.volatile=state";
+        fi
+    fi
 ## \" required for snap,kernels,init,microcode with space in their name
-    entry "submenu '$title_menu' {
+    entry "submenu '${title_menu}' {
-    submenu '---> $title_menu <---' { echo }"
+    submenu '${title_submenu}' { echo }"
     for k in "${name_kernel[@]}"; do
         [[ ! -f "${boot_dir}"/"${k}" ]] && continue;
         kversion=${k#*"-"}
         for i in "${name_initramfs[@]}"; do
-            prefix_i=${i%%"-"*}
+            if [[ "${name_initramfs}" != "x" ]] ; then
-            suffix_i=${i#*"-"}
+                # prefix_i=${i%%"-"*}
-            alt_suffix_i=${i##*"-"}
+                suffix_i=${i#*"-"}
-            if   [ "${kversion}" = "${suffix_i}" ];                 then i="${i}";
+                # alt_suffix_i=${i##*"-"}
-            elif [ "${kversion}.img" = "${suffix_i}" ];             then i="${i}";
+                if   [ "${kversion}" = "${suffix_i}" ];                 then i="${i}";
-            elif [ "${kversion}-fallback.img" = "${suffix_i}" ];    then i="${i}";
+                elif [ "${kversion}.img" = "${suffix_i}" ];             then i="${i}";
-            elif [ "${kversion}.gz" = "${suffix_i}" ];              then i="${i}";
+                elif [ "${kversion}-fallback.img" = "${suffix_i}" ];    then i="${i}";
-            else continue ;
+                elif [ "${kversion}.gz" = "${suffix_i}" ];              then i="${i}";
-            fi
+                else continue;
-            for u in "${name_microcode[@]}"; do
-                if [[ "${name_microcode}" != "x" ]] ; then
-                    entry "
-    menuentry '"${k}" & "${i}" & "${u}"' ${CLASS} "\$menuentry_id_option" 'gnulinux-snapshots-$boot_uuid' {"
-                else
-                    entry "
-    menuentry '"${k}" & "${i}"' ${CLASS} "\$menuentry_id_option" 'gnulinux-snapshots-$boot_uuid' {"
                 fi
-                entry "\
+                for u in "${name_microcode[@]}"; do
+                    if [[ "${name_microcode}" != "x" ]] ; then
+                    entry "
+    menuentry '  "${k}" & "${i}" & "${u}"' ${CLASS} "\$menuentry_id_option" 'gnulinux-snapshots-$boot_uuid' {"
+                    else
+                    entry "
+    menuentry '  "${k}" & "${i}"' ${CLASS} "\$menuentry_id_option" 'gnulinux-snapshots-$boot_uuid' {"
+                    fi
+                    entry "\
         if [ x\$feature_all_video_module = xy ]; then
         insmod all_video
         fi
@@ -181,21 +208,53 @@ make_menu_entries()
         else
             search --no-floppy --fs-uuid  --set=root ${boot_uuid}
         fi
-        echo 'Loading Snapshot: "${snap_date_time}" "${snap_dir_name}"'
+        echo 'Loading Snapshot: "${snap_date_trim}" "${snap_dir_name_trim}"'
         echo 'Loading Kernel: "${k}" ...'
-        linux \"${boot_dir_root_grub}/"${k}"\" root="${LINUX_ROOT_DEVICE}" rw ${kernel_parameters} rootflags=subvol=\""${snap_dir_name}"\""
+        linux \"${boot_dir_root_grub}/"${k}"\" root="${LINUX_ROOT_DEVICE}" ${kernel_parameters} ${rootflags}subvol=\""${snap_dir_name_trim}"\""
-                if [[ "${name_microcode}" != "x" ]] ; then
+                    if [[ "${name_microcode}" != "x" ]] ; then
-                    entry "\
+                        entry "\
         echo 'Loading Microcode & Initramfs: "${u}" "${i}" ...'
         initrd \"${boot_dir_root_grub}/"${u}"\" \"${boot_dir_root_grub}/"${i}"\""
-                else
+                    else
-                    entry "\
+                        entry "\
         echo 'Loading Initramfs: "${i}" ...'
         initrd \"${boot_dir_root_grub}/"${i}"\""
-                fi
+                    fi
-                entry "    }"
+                    entry "    }"
-                count_warning_menuentries=$((1+$count_warning_menuentries))
+                    count_warning_menuentries=$((1+count_warning_menuentries))
-            done
+                done
+            else
+                for u in "${name_microcode[@]}"; do
+                    if [[ "${name_microcode}" != "x" ]] ; then
+                    entry "
+    menuentry '  "${k}" & "${u}"' ${CLASS} "\$menuentry_id_option" 'gnulinux-snapshots-$boot_uuid' {"
+                    else
+                    entry "
+    menuentry '  "${k}"' ${CLASS} "\$menuentry_id_option" 'gnulinux-snapshots-$boot_uuid' {"
+                    fi
+                    entry "\
+        if [ x\$feature_all_video_module = xy ]; then
+        insmod all_video
+        fi
+        set gfxpayload=keep
+        insmod ${boot_fs}
+        if [ x\$feature_platform_search_hint = xy ]; then
+            search --no-floppy --fs-uuid  --set=root ${boot_hs} ${boot_uuid}
+        else
+            search --no-floppy --fs-uuid  --set=root ${boot_uuid}
+        fi
+        echo 'Loading Snapshot: "${snap_date_trim}" "${snap_dir_name_trim}"'
+        echo 'Loading Kernel: "${k}" ...'
+        linux \"${boot_dir_root_grub}/"${k}"\" root="${LINUX_ROOT_DEVICE}" ${kernel_parameters} ${rootflags}subvol=\""${snap_dir_name_trim}"\""
+                    if [[ "${name_microcode}" != "x" ]] ; then
+                        entry "\
+        echo 'Loading Microcode: "${u}" ...'
+        initrd \"${boot_dir_root_grub}/"${u}"\""
+                    fi
+                    entry "    }"
+                    count_warning_menuentries=$((1+count_warning_menuentries))
+                done
+            fi
         done
     done
     entry  "}"
@@ -212,98 +271,117 @@ trim() {
 ## List of snapshots on filesystem
 snapshot_list()
 {
-    # Query info from snapper if it is installed
+    local snapper_info="info.xml"
-    type snapper >/dev/null 2>&1
+    local timeshift_info="info.json"
-    if [ $? -eq 0 ]; then
+    local date_snapshots=()
-        if [ -s "/etc/snapper/configs/$snapper_config" ]; then
+    local path_snapshots=()
-            printf "Info: snapper detected, using config '$snapper_config'\n" >&2
+    local type_snapshots=()
-            local snapper_ids=($(snapper --no-dbus -t 0 -c "$snapper_config" list --disable-used-space | tail -n +3 | cut -d'|' -f 1))
+    local description_snapshots=()
-            local snapper_types=($(snapper --no-dbus -t 0 -c "$snapper_config" list --disable-used-space | tail -n +3 | cut -d'|' -f 2))
-
-            IFS=$'\n'
-            local snapper_descriptions=($(snapper --no-dbus -t 0 -c "$snapper_config" list --disable-used-space | tail -n +3 | rev | cut -d'|' -f 2 | rev))
-        else
-            printf "Warning: snapper detected but config '$snapper_config' does not exist\n" >&2
-        fi
-    fi
-
     IFS=$'\n'
-
+    for snap in $(btrfs subvolume list -sa "${btrfs_subvolume_sort}" /); do # Parse btrfs snapshots
-    # Parse btrfs snapshots
-    local entries=()
-    local ids=()
-    local max_entry_length=0
-    for snap in $(btrfs subvolume list -sa "${btrfssubvolsort}" /); do
         IFS=$oldIFS
         snap=($snap)
-        local snap_path_name=${snap[@]:13:${#snap[@]}}
+        local path_snapshot=${snap[@]:13:${#snap[@]}}
-
+        if [ "$path_snapshot" = "DELETED" ]; then continue; fi # Discard deleted snapshots
-        # Discard deleted snapshots
+        [[ ${path_snapshot%%"/"*} == "<FS_TREE>" ]] && path_snapshot=${path_snapshot#*"/"} # Remove the "<FS_TREE>" string at the beginning of the path
-        if [ "$snap_path_name" = "DELETED" ]; then continue; fi
-        [[ ${snap_path_name%%"/"*} == "<FS_TREE>" ]] && snap_path_name=${snap_path_name#*"/"}
 
         # ignore specific path during run "grub-mkconfig"
-        if [ ! -z "${GRUB_BTRFS_IGNORE_SPECIFIC_PATH}" ] ; then
+        if [ -n "${GRUB_BTRFS_IGNORE_SPECIFIC_PATH}" ] ; then
-            for isp in ${GRUB_BTRFS_IGNORE_SPECIFIC_PATH[@]} ; do
+            for isp in "${GRUB_BTRFS_IGNORE_SPECIFIC_PATH[@]}" ; do
-                [[ "${snap_path_name}" == "${isp}" ]] && continue 2;
+                [[ "${path_snapshot}" == "${isp}" ]] && continue 2;
             done
         fi
-        if [ ! -z "${GRUB_BTRFS_IGNORE_PREFIX_PATH}" ] ; then
+        if [ -n "${GRUB_BTRFS_IGNORE_PREFIX_PATH}" ] ; then
-            for isp in ${GRUB_BTRFS_IGNORE_PREFIX_PATH[@]} ; do
+            for isp in "${GRUB_BTRFS_IGNORE_PREFIX_PATH[@]}" ; do
-                [[ "${snap_path_name}" == "${isp}"/* ]] && continue 2;
+                [[ "${path_snapshot}" == "${isp}"/* ]] && continue 2;
+            done
+        fi
+        [[ ! -d "$grub_btrfs_mount_point/$path_snapshot/boot" ]] && continue; # Discard snapshots without /boot folder
+
+        # Parse Snapper & timeshift informations
+        local type_snapshot="N/A"
+        local description_snapshot="N/A"
+        if [[ -s "$grub_btrfs_mount_point/${path_snapshot%"/"*}/$snapper_info" ]] ; then
+            type_snapshot=$(awk -F"<|>" 'match($2, /^type/) {print $3}' "$grub_btrfs_mount_point/${path_snapshot%"/"*}/$snapper_info") # search matching string beginning "type"
+            description_snapshot=$(awk -F"<|>" 'match($2, /^description/) {print $3}' "$grub_btrfs_mount_point/${path_snapshot%"/"*}/$snapper_info") # search matching string beginning "description"
+        elif [[ -s "$grub_btrfs_mount_point/${path_snapshot%"/"*}/$timeshift_info" ]] ; then
+            type_snapshot=$(awk -F" : " 'match($1, /^[ \t]+"tags"/) {gsub(/"|,/,"");print $2}' "$grub_btrfs_mount_point/${path_snapshot%"/"*}/$timeshift_info") # search matching string beginning "tags"
+            description_snapshot=$(awk -F" : " 'match($1, /^[ \t]+"comments"/) {gsub(/"|,/,"");print $2}' "$grub_btrfs_mount_point/${path_snapshot%"/"*}/$timeshift_info") # search matching string beginning "comments"
+        fi
+        [[ -z "$type_snapshot" ]] && type_snapshot=("N/A")
+        [[ -z "$description_snapshot" ]] && description_snapshot=("N/A")
+
+        # ignore specific {type,tag,description} of snapshot during run "grub-mkconfig"
+        if [ -n "${GRUB_BTRFS_IGNORE_SNAPSHOT_TYPE}" ] ; then
+            for ist in "${GRUB_BTRFS_IGNORE_SNAPSHOT_TYPE[@]}" ; do
+                [[ "${type_snapshot}" == "${ist}" ]] && continue 2;
+            done
+        fi
+        if [ -n "${GRUB_BTRFS_IGNORE_SNAPSHOT_DESCRIPTION}" ] ; then
+            for isd in "${GRUB_BTRFS_IGNORE_SNAPSHOT_DESCRIPTION[@]}" ; do
+                [[ "${description_snapshot}" == "${isd}" ]] && continue 2;
             done
         fi
 
-        # detect if /boot directory exists
+        local date_snapshot="${snap[@]:10:2}"
-        [[ ! -d "$gbgmp/$snap_path_name/boot" ]] && continue;
+        date_snapshots+=("$date_snapshot")
+        path_snapshots+=("$path_snapshot")
+        type_snapshots+=("$type_snapshot")
+        description_snapshots+=("$description_snapshot")
+    done
 
-        local id="${snap_path_name//[!0-9]}" # brutal way to get id: remove everything non-numeric
+    # Find max length of a snapshot date, needed for pretty formatting
-        ids+=("$id")
+    local max_date_length=0
+    for i in "${date_snapshots[@]}"; do
+        local length="${#i}"
+        [[ "$length" -gt "$max_date_length" ]] && max_date_length=$length
+    done
 
-        local entry="${snap[@]:10:2} | ${snap_path_name}"
+    # Find max length of a snapshot name, needed for pretty formatting
-        entries+=("$entry")
+    local max_path_length=0
-
+    for i in "${path_snapshots[@]}"; do
-        # Find max length of a snapshot entry, needed for pretty formatting
+        local length="${#i}"
-        local length="${#entry}"
+        [[ "$length" -gt "$max_path_length" ]] && max_path_length=$length
-        [[ "$length" -gt "$max_entry_length" ]] && max_entry_length=$length
     done
 
     # Find max length of a snapshot type, needed for pretty formatting
     local max_type_length=0
-    for id in "${ids[@]}"; do
+    for i in "${type_snapshots[@]}"; do
-        for j in "${!snapper_ids[@]}"; do
+        local length="${#i}"
-            local snapper_id="${snapper_ids[$j]//[[:space:]]/}"
+        [[ "$length" -gt "$max_type_length" ]] && max_type_length=$length
-            if [[ "$snapper_id" == "$id" ]]; then
-                local snapper_type=$(trim "${snapper_types[$j]}")
-                local length="${#snapper_type}"
-                [[ "$length" -gt "$max_type_length" ]] && max_type_length=$length
-            fi
-        done
     done
 
-    for i in "${!entries[@]}"; do
+    # Find max length of a snapshot description, needed for pretty formatting
-        local id="${ids[$i]}"
+    local max_description_length=0
-        local entry="${entries[$i]}"
+    for i in "${description_snapshots[@]}"; do
-        for j in "${!snapper_ids[@]}"; do
+        local length="${#i}"
-            local snapper_id="${snapper_ids[$j]//[[:space:]]/}"
+        [[ "$length" -gt "$max_description_length" ]] && max_description_length=$length
-            # remove other non numeric characters
+    done
-            snapper_id="${snapper_id//\*/}"
+
-            snapper_id="${snapper_id//\+/}"
+    for i in "${!path_snapshots[@]}"; do
-            snapper_id="${snapper_id//-/}"
+        printf -v entry "%-${max_date_length}s | %-${max_path_length}s | %-${max_type_length}s | %-${max_description_length}s |" "${date_snapshots[$i]}" "${path_snapshots[$i]}" "${type_snapshots[$i]}" "${description_snapshots[$i]}"
-            if [[ "$snapper_id" == "$id" ]]; then
-                local snapper_type=$(trim "${snapper_types[$j]}")
-                local snapper_description=$(trim "${snapper_descriptions[$j]}")
-                printf -v entry "%-${max_entry_length}s | %-${max_type_length}s | %s" "$entry" "$snapper_type" "$snapper_description"
-                break
-            fi
-        done
         echo "$entry"
     done
 
     IFS=$oldIFS
 }
 
-## Detect kernels in "/boot"
+## Parse snapshots in snapshot_list
+parse_snapshot_list()
+{
+    snap_date=" $(echo "$item" | cut -d'|' -f1)" # column_1, first space is necessary for pretty formatting
+    snap_date_trim="$(trim "$snap_date")"
+
+    snap_dir_name="$(echo "$item" | cut -d'|' -f2)" # column_2
+    snap_dir_name_trim="$(trim "$snap_dir_name")"
+    snap_snapshot="$snap_dir_name" # Used by "title_format" function
+
+    snap_type="$(echo "$item" | cut -d'|' -f3)" # column_3
+
+    snap_description="$(echo "$item" | cut -d'|' -f4)" # column_4
+}
+
+## Detect kernels in "boot_directory"
 detect_kernel()
 {
     list_kernel=()
@@ -315,8 +393,8 @@ detect_kernel()
         list_kernel+=("$okernel")
     done
 
-    # Custom name kernel in GRUB_BTRFS_NKERNEL
+    # Custom name kernel in "GRUB_BTRFS_NKERNEL"
-    if [ ! -z "${GRUB_BTRFS_NKERNEL}" ] ; then
+    if [ -n "${GRUB_BTRFS_NKERNEL}" ] ; then
         for ckernel in "${boot_dir}/${GRUB_BTRFS_NKERNEL[@]}" ; do
             [[ ! -f "${ckernel}" ]] && continue;
             list_kernel+=("$ckernel")
@@ -324,30 +402,29 @@ detect_kernel()
     fi
 }
 
-## Detect initramfs in "/boot"
+## Detect initramfs in "boot_directory"
 detect_initramfs()
 {
     list_initramfs=()
     # Original initramfs (auto-detect)
     for oinitramfs in   "${boot_dir}"/initrd.img-* \
-                        "${boot_dir}"/initrd-*.img \
+                        "${boot_dir}"/initramfs-* \
-                        "${boot_dir}"/initrd-*.gz \
+                        "${boot_dir}"/initrd-* ; do
-                        "${boot_dir}"/initramfs-*.img \
-                        "${boot_dir}"/initramfs-*.gz ; do
         [[ ! -f "${oinitramfs}" ]] && continue;
         list_initramfs+=("$oinitramfs")
     done
 
-    # Custom name initramfs in GRUB_BTRFS_NINIT
+    # Custom name initramfs in "GRUB_BTRFS_NINIT"
-    if [ ! -z "${GRUB_BTRFS_NINIT}" ] ; then
+    if [ -n "${GRUB_BTRFS_NINIT}" ] ; then
         for cinitramfs in "${boot_dir}/${GRUB_BTRFS_NINIT[@]}" ; do
             [[ ! -f "${cinitramfs}" ]] && continue;
             list_initramfs+=("$cinitramfs")
         done
     fi
+    if [ -z "${list_initramfs}" ]; then list_initramfs=(x); fi
 }
 
-## Detect microcode in "/boot"
+## Detect microcode in "boot_directory"
 detect_microcode()
 {
     list_ucode=()
@@ -363,8 +440,8 @@ detect_microcode()
         list_ucode+=("$oiucode")
     done
 
-    # Custom name microcode in GRUB_BTRFS_CUSTOM_MICROCODE
+    # Custom name microcode in "GRUB_BTRFS_CUSTOM_MICROCODE"
-    if [ ! -z "${GRUB_BTRFS_CUSTOM_MICROCODE}" ] ; then
+    if [ -n "${GRUB_BTRFS_CUSTOM_MICROCODE}" ] ; then
         for cucode in "${boot_dir}/${GRUB_BTRFS_CUSTOM_MICROCODE[@]}" ; do
             [[ ! -f "${cucode}" ]] && continue
             list_ucode+=("$cucode")
@@ -373,29 +450,39 @@ detect_microcode()
     if [ -z "${list_ucode}" ]; then list_ucode=(x); fi
 }
 
-## Show full path snapshot or only name
+## Title format in Grub-menu
-path_snapshot()
+declare -A title_column=( [date]=Date [snapshot]=Snapshot [type]=Type [description]=Description ) # Column title that appears in the header
-{
-    case "${GRUB_BTRFS_DISPLAY_PATH_SNAPSHOT:-"true"}" in
-        true) name_snapshot=("${snap_full_name}");;
-        *)    name_snapshot=("${snap_full_name#*"/"}")
-    esac
-}
-
-## Title format in grub-menu
 title_format()
 {
-    case "${GRUB_BTRFS_TITLE_FORMAT:-"p/d/n"}" in
+    title_menu="|" # "|" is for visuals only
-        p/n/d)  title_menu="${prefixentry} ${name_snapshot} ${snap_date_time}";;
+    title_submenu="|" # "|" is for visuals only
-        p/d)    title_menu="${prefixentry} ${snap_date_time}";;
+    [[ -z "${GRUB_BTRFS_TITLE_FORMAT}" ]] && GRUB_BTRFS_TITLE_FORMAT=("date" "snapshot" "type" "description"); # Default parameters
-        p/n)    title_menu="${prefixentry} ${name_snapshot}";;
+    for key in "${!GRUB_BTRFS_TITLE_FORMAT[@]}"; do
-        d/n)    title_menu="${snap_date_time} ${name_snapshot}";;
+            [[ ${GRUB_BTRFS_TITLE_FORMAT[$key],,} != "${title_column[${GRUB_BTRFS_TITLE_FORMAT[$key]}],,}" ]] && continue; # User used wrong parameter
-        n/d)    title_menu="${name_snapshot} ${snap_date_time}";;
+            declare -n var="snap_${GRUB_BTRFS_TITLE_FORMAT[$key],,}" # $var is a indirect variable
-        p)      title_menu="${prefixentry}";;
+            if [[ "${#var}" -lt "${#title_column[${GRUB_BTRFS_TITLE_FORMAT[$key],,}]}" ]]; then # Add extra spaces if length of $var is smaller than the length of column, needed for pretty formatting
-        d)      title_menu="${snap_date_time}";;
+                printf -v var "%-$(((${#title_column[${GRUB_BTRFS_TITLE_FORMAT[$key],,}]}-${#var})+${#var}))s" "${var}";
-        n)      title_menu="${name_snapshot}";;
+            fi
-        *)      title_menu="${prefixentry} ${snap_date_time} ${name_snapshot}"
+            title_menu+="${var}|"
-    esac
+            title_submenu+=" $(trim "${var}") |"
+    done
+}
+# Adds a header to the grub-btrfs.cfg file
+header_menu()
+{
+    local header_entry=""
+    [[ -z "${GRUB_BTRFS_TITLE_FORMAT}" ]] && GRUB_BTRFS_TITLE_FORMAT=("date" "snapshot" "type" "description"); # Default parameters
+        for key in "${!GRUB_BTRFS_TITLE_FORMAT[@]}"; do
+            [[ ${GRUB_BTRFS_TITLE_FORMAT[$key],,} != "${title_column[${GRUB_BTRFS_TITLE_FORMAT[$key]}],,}" ]] && continue; # User used wrong parameter
+            declare -n var="snap_${GRUB_BTRFS_TITLE_FORMAT[$key],,}" # $var is a indirect variable
+            # Center alignment, needed for pretty formatting
+            local lenght_title_column_left=$((${#var}-${#title_column[${GRUB_BTRFS_TITLE_FORMAT[$key],,}]}))
+            ((lenght_title_column_left%2)) && lenght_title_column_left=$((lenght_title_column_left+1));  # If the difference is an odd number, add an extra space
+            lenght_title_column_left=$((((lenght_title_column_left/2)+${#title_column[${GRUB_BTRFS_TITLE_FORMAT[$key],,}]})));
+            local lenght_title_column_right=$(((${#var}-lenght_title_column_left)+1)) #+1 is necessary for extra "|" character
+            header_entry+=$(printf "%${lenght_title_column_left}s%${lenght_title_column_right}s" "${title_column[${GRUB_BTRFS_TITLE_FORMAT[$key],,}]}" "|") # Final "|" is for visuals only
+        done
+    sed -i "1imenuentry '|${header_entry}' { echo }" "$grub_directory/grub-btrfs.new" # First "|" is for visuals only
 }
 
 ## List of kernels, initramfs and microcode in snapshots
@@ -406,59 +493,39 @@ boot_bounded()
     for item in $(snapshot_list); do
         [[ ${limit_snap_show} -le 0 ]] && break; # fix: limit_snap_show=0
         IFS=$oldIFS
-        snap_full_name="$(echo "$item" | cut -d'|' -f2-)" # do not trim it to keep nice formatting
+        parse_snapshot_list
-        snap_dir_name="$(echo "$item" | cut -d'|' -f2)"
+        boot_dir="$grub_btrfs_mount_point/$snap_dir_name_trim$boot_directory"
-        snap_dir_name="$(trim "$snap_dir_name")"
-        snap_date_time="$(echo "$item" | cut -d' ' -f1-2)"
-        snap_date_time="$(trim "$snap_date_time")"
-        
-        boot_dir="$gbgmp/$snap_dir_name$boot_directory"
-        # Kernel (Original + custom kernel)
         detect_kernel
         if [ -z "${list_kernel}" ]; then continue; fi
         name_kernel=("${list_kernel[@]##*"/"}")
-        # Initramfs (Original + custom initramfs)
         detect_initramfs
-        if [ -z "${list_initramfs}" ]; then continue; fi
         name_initramfs=("${list_initramfs[@]##*"/"}")
-        # microcode (auto-detect + custom microcode)
         detect_microcode
         name_microcode=("${list_ucode[@]##*"/"}")
+        detect_rootflags
+        title_format
+        boot_dir_root_grub="$(make_system_path_relative_to_its_root "${boot_dir}")" # convert "boot_directory" to root of GRUB (e.g /boot become /)
+        make_menu_entries
         # show snapshot found during run "grub-mkconfig"
         if [[ "${GRUB_BTRFS_SHOW_SNAPSHOTS_FOUND:-"true"}" = "true" ]]; then
             printf "Found snapshot: %s\n" "$item" >&2 ;
         fi
-        # Show full path snapshot or only name
+        # Limit snapshots found during run "grub-mkconfig"
-        path_snapshot
+        count_limit_snap=$((1+count_limit_snap))
-        # Title format in grub-menu
-        title_format
-        # convert /boot directory to root of GRUB (e.g /boot become /)
-        boot_dir_root_grub="$(make_system_path_relative_to_its_root "${boot_dir}")"
-        # Make menuentries
-        make_menu_entries
-        ### Limit snapshots found during run "grub-mkconfig"
-        count_limit_snap=$((1+$count_limit_snap))
         [[ $count_limit_snap -ge $limit_snap_show ]] && break;
-        # Limit generation of menuentries if exceeds 250
-        # [[ $count_warning_menuentries -ge 250 ]] && break;
     done
     IFS=$oldIFS
 }
+
 boot_separate()
 {
     boot_dir="${boot_directory}"
-    # convert /boot directory to root of GRUB (e.g /boot become /)
+    boot_dir_root_grub="$(make_system_path_relative_to_its_root "${boot_dir}")" # convert "boot_directory" to root of GRUB (e.g /boot become /)
-    boot_dir_root_grub="$(make_system_path_relative_to_its_root "${boot_dir}")"
-
-    # Kernel (Original + custom kernel)
     detect_kernel
     if [ -z "${list_kernel}" ]; then print_error "Kernels not found."; fi
     name_kernel=("${list_kernel[@]##*"/"}")
-    # Initramfs (Original + custom initramfs)
     detect_initramfs
-    if [ -z "${list_initramfs}" ]; then print_error "Initramfs not found."; fi
     name_initramfs=("${list_initramfs[@]##*"/"}")
-    # microcode (auto-detect + custom microcode)
     detect_microcode
     name_microcode=("${list_ucode[@]##*"/"}")
 
@@ -467,76 +534,53 @@ boot_separate()
     for item in $(snapshot_list); do
         [[ ${limit_snap_show} -le 0 ]] && break; # fix: limit_snap_show=0
         IFS=$oldIFS
-        snap_full_name="$(echo "$item" | cut -d'|' -f2-)" # do not trim it to keep nice formatting
+        parse_snapshot_list
-        snap_dir_name="$(echo "$item" | cut -d'|' -f2)"
+        detect_rootflags
-        snap_dir_name="$(trim "$snap_dir_name")"
+        title_format
-        snap_date_time="$(echo "$item" | cut -d' ' -f1-2)"
+        make_menu_entries
-        snap_date_time="$(trim "$snap_date_time")"
         # show snapshot found during run "grub-mkconfig"
         if [[ "${GRUB_BTRFS_SHOW_SNAPSHOTS_FOUND:-"true"}" = "true" ]]; then
             printf "Found snapshot: %s\n" "$item" >&2 ;
         fi
-        # Show full path snapshot or only name
-        path_snapshot
-        # Title format in grub-menu
-        title_format
-        # Make menuentries
-        make_menu_entries
         # Limit snapshots found during run "grub-mkconfig"
-        count_limit_snap=$((1+$count_limit_snap))
+        count_limit_snap=$((1+count_limit_snap))
         [[ $count_limit_snap -ge $limit_snap_show ]] && break;
-        # Limit generation of menuentries if exceeds 250
-        # [[ $count_warning_menuentries -ge 250 ]] && break;
     done
     IFS=$oldIFS
 }
 
-### Start
+rm -f "$grub_directory/grub-btrfs.new"
-printf "Detecting snapshots ...\n" >&2 ;
+> "$grub_directory/grub-btrfs.new" # Create a "grub-btrfs.new" file in "grub_directory"
-# Only support btrfs snapshots
-test_btrfs
-# Delete existing config
-#rm -f --preserve-root "$grub_directory/grub-btrfs.cfg"
-> "$grub_directory/grub-btrfs.cfg"
 # Create mount point then mounting
-[[ ! -d $gbgmp ]] && mkdir -p $gbgmp
+[[ ! -d $grub_btrfs_mount_point ]] && mkdir -p "$grub_btrfs_mount_point"
-mount -o subvolid=5 /dev/disk/by-uuid/$root_uuid $gbgmp/
+mount -o ro,subvolid=5 /dev/disk/by-uuid/"$root_uuid" "$grub_btrfs_mount_point/"
-# Count menuentries
+trap "unmount_grub_btrfs_mount_point" EXIT # unmounting mount point on EXIT signal
-count_warning_menuentries=0
+count_warning_menuentries=0 # Count menuentries
-# Count snapshots
+count_limit_snap=0 # Count snapshots
-count_limit_snap=0
-# detect uuid requirement
 check_uuid_required
 # Detects if /boot is a separate partition
-if [[ "${GRUB_BTRFS_OVERRIDE_BOOT_PARTITION_DETECTION:-"false"}" == "true" ]]; then
+[[ "${GRUB_BTRFS_OVERRIDE_BOOT_PARTITION_DETECTION,,}" == "true" ]] && printf "Override boot partition detection : enable \n" >&2 && boot_separate;
-    printf "Info: Override boot partition detection : enable \n" >&2 ;
+if [[ "$root_uuid" != "$boot_uuid" ]] || [[ "$root_uuid_subvolume" != "$boot_uuid_subvolume" ]]; then boot_separate ; else boot_bounded ; fi
-    boot_separate
-else
-    if [[ "$root_uuid" != "$boot_uuid" ]]; then
-        printf "Info: Separate boot partition detected \n" >&2 ;
-        boot_separate
-    else
-        printf "Info: Separate boot partition not detected \n" >&2 ;
-        boot_bounded
-    fi
-fi
-# unmounting mount point
-umount $gbgmp
 # Show warn, menuentries exceeds 250 entries
-[[ $count_warning_menuentries -ge 250 ]] && printf "Generated ${count_warning_menuentries} total GRUB entries. You might experience issues loading snapshots menu in GRUB.\n" >&2 ;
+[[ $count_warning_menuentries -ge 250 ]] && printf "Generated %s total GRUB entries. You might experience issues loading snapshots menu in GRUB.\n" "${count_warning_menuentries}" >&2 ;
-# printf "menuentries = $count_warning_menuentries \n" >&2 ;
 # Show total found snapshots
-if [[ "${GRUB_BTRFS_SHOW_TOTAL_SNAPSHOTS_FOUND:-"true"}" = "true" && ! -z "${count_limit_snap}" && "${count_limit_snap}" != "0" ]]; then
+if [[ "${GRUB_BTRFS_SHOW_TOTAL_SNAPSHOTS_FOUND:-"true"}" = "true" && -n "${count_limit_snap}" && "${count_limit_snap}" != "0" ]]; then
-    printf "Found ${count_limit_snap} snapshot(s)\n" >&2 ;
+    printf "Found %s snapshot(s)\n" "${count_limit_snap}" >&2 ;
 fi
 # if no snapshot found, exit
 if [[ "${count_limit_snap}" = "0" || -z "${count_limit_snap}" ]]; then
     print_error "No snapshots found."
 fi
-# Make a submenu in GRUB (grub.cfg)
+# Make a submenu in GRUB (grub.cfg) and move "grub-btrfs.new" to "grub-btrfs.cfg"
-cat << EOF
+header_menu
+if "${bindir}/${GRUB_BTRFS_SCRIPT_CHECK:-grub-script-check}" "$grub_directory/grub-btrfs.new"; then
+    cat "$grub_directory/grub-btrfs.new" > "$grub_directory/grub-btrfs.cfg"
+    rm -f "$grub_directory/grub-btrfs.new"
+    cat << EOF
 submenu '${submenuname}' ${protection_authorized_users}${unrestricted_access_submenu}{
     configfile "\${prefix}/grub-btrfs.cfg"
 }
 EOF
-### End
+else
+    print_error "Syntax errors are detected in generated grub-btrfs.cfg file."
+fi

Makefile

@@ -1,31 +1,86 @@
 PKGNAME ?= grub-btrfs
 PREFIX ?= /usr
 
+INITCPIO ?= false
+SYSTEMD ?= true
+OPENRC ?= false
+
 SHARE_DIR = $(DESTDIR)$(PREFIX)/share
 LIB_DIR = $(DESTDIR)$(PREFIX)/lib
+BIN_DIR = $(DESTDIR)$(PREFIX)/bin
 
-.PHONY: install
+.PHONY: install uninstall help
 
 install:
+	@if test "$(shell id -u)" != 0; then \
+		echo "You are not root, run this target as root please."; \
+		exit 1; \
+	fi
 	@install -Dm755 -t "$(DESTDIR)/etc/grub.d/" 41_snapshots-btrfs
 	@install -Dm644 -t "$(DESTDIR)/etc/default/grub-btrfs/" config
-	@install -Dm644 -t "$(LIB_DIR)/systemd/system/" grub-btrfs.service
+	@# Systemd init system
-	@install -Dm644 -t "$(LIB_DIR)/systemd/system/" grub-btrfs.path
+	@if test "$(SYSTEMD)" = true; then \
+		install -Dm644 -t "$(LIB_DIR)/systemd/system/" grub-btrfs.path; \
+		install -Dm644 -t "$(LIB_DIR)/systemd/system/" grub-btrfs.service; \
+	 fi
+	@# OpenRC init system
+	@if test "$(OPENRC)" = true; then \
+		install -Dm744 -t "$(BIN_DIR)/" grub-btrfs-openrc; \
+		install -Dm744 -t "$(DESTDIR)/etc/init.d/" grub-btrfsd; \
+	 fi
+	@# Arch Linux like distros only :
+	@if test "$(INITCPIO)" = true; then \
+		install -Dm644 "initramfs/Arch Linux/overlay_snap_ro-install" "$(LIB_DIR)/initcpio/install/grub-btrfs-overlayfs"; \
+		install -Dm644 "initramfs/Arch Linux/overlay_snap_ro-hook" "$(LIB_DIR)/initcpio/hooks/grub-btrfs-overlayfs"; \
+	 fi
 	@install -Dm644 -t "$(SHARE_DIR)/licenses/$(PKGNAME)/" LICENSE
-	@install -Dm644 "initramfs/Arch Linux/overlay_snap_ro-install" "$(LIB_DIR)/initcpio/install/grub-btrfs-overlayfs"	# Arch Linux only
-	@install -Dm644 "initramfs/Arch Linux/overlay_snap_ro-hook" "$(LIB_DIR)/initcpio/hooks/grub-btrfs-overlayfs"		# Arch Linux only
 	@install -Dm644 -t "$(SHARE_DIR)/doc/$(PKGNAME)/" README.md
 	@install -Dm644 "initramfs/readme.md" "$(SHARE_DIR)/doc/$(PKGNAME)/initramfs-overlayfs.md"
 
 uninstall:
-	rm -f "$(DESTDIR)/etc/grub.d/41_snapshots-btrfs"
+	@if test "$(shell id -u)" != 0; then \
-	rm -f "$(DESTDIR)/etc/default/grub-btrfs/config"
+		echo "You are not root, run this target as root please."; \
-	rm -f "$(LIB_DIR)/systemd/system/grub-btrfs.service"
+		exit 1; \
-	rm -f "$(LIB_DIR)/systemd/system/grub-btrfs.path"
+	fi
-	rm -f "$(SHARE_DIR)/licenses/$(PKGNAME)/LICENSE"
+	@grub_dirname="$$(grep -oP '^[[:space:]]*GRUB_BTRFS_GRUB_DIRNAME=\K.*' "$(DESTDIR)/etc/default/grub-btrfs/config" | sed "s|\s*#.*||;s|(\s*\(.\+\)\s*)|\1|;s|['\"]||g")"; \
-	rm -f "$(DESTDIR)/boot/grub/grub-btrfs.cfg"
+	 rm -f "$${grub_dirname:-/boot/grub}/grub-btrfs.cfg"
-	rm -f "$(LIB_DIR)/initcpio/install/grub-btrfs-overlayfs" # Arch Linux only
+	@rm -f "$(DESTDIR)/etc/default/grub-btrfs/config"
-	rm -f "$(LIB_DIR)/initcpio/hooks/grub-btrfs-overlayfs" # Arch Linux only
+	@rm -f "$(DESTDIR)/etc/grub.d/41_snapshots-btrfs"
-	rm -rf "$(SHARE_DIR)/doc/$(PKGNAME)/" README.md
+	@rm -f "$(LIB_DIR)/systemd/system/grub-btrfs.path"
-	rm -rf "$(SHARE_DIR)/doc/$(PKGNAME)/initramfs-overlayfs.md"
+	@rm -f "$(LIB_DIR)/systemd/system/grub-btrfs.service"
-	rmdir --ignore-fail-on-non-empty "$(DESTDIR)/etc/default/grub-btrfs"
+	@rm -f "$(BIN_DIR)/grub-btrfs-openrc;"
+	@rm -f "$(DESTDIR)/etc/init.d/grub-btrfsd;"
+	@rm -f "$(LIB_DIR)/initcpio/install/grub-btrfs-overlayfs"
+	@rm -f "$(LIB_DIR)/initcpio/hooks/grub-btrfs-overlayfs"
+	@# Arch Linux UNlike distros only :
+	@if test "$(INITCPIO)" != true && test -d "$(LIB_DIR)/initcpio"; then \
+		rmdir --ignore-fail-on-non-empty "$(LIB_DIR)/initcpio/install" || :; \
+		rmdir --ignore-fail-on-non-empty "$(LIB_DIR)/initcpio/hooks" || :; \
+		rmdir --ignore-fail-on-non-empty "$(LIB_DIR)/initcpio" || :; \
+	 fi
+	@rm -f "$(SHARE_DIR)/doc/$(PKGNAME)/README.md"
+	@rm -f "$(SHARE_DIR)/doc/$(PKGNAME)/initramfs-overlayfs.md"
+	@rm -f "$(SHARE_DIR)/licenses/$(PKGNAME)/LICENSE"
+	@rmdir --ignore-fail-on-non-empty "$(SHARE_DIR)/doc/$(PKGNAME)/" || :
+	@rmdir --ignore-fail-on-non-empty "$(SHARE_DIR)/licenses/$(PKGNAME)/" || :
+	@rmdir --ignore-fail-on-non-empty "$(DESTDIR)/etc/default/grub-btrfs" || :
+
+help:
+	@echo
+	@echo "Usage: $(MAKE) [ <parameter>=<value> ... ] [ <action> ]"
+	@echo
+	@echo "  actions: install"
+	@echo "           uninstall"
+	@echo "           help"
+	@echo
+	@echo "  parameter | type | description                    | defaults"
+	@echo "  ----------+------+--------------------------------+----------------------------"
+	@echo "  DESTDIR   | path | install destination            | <unset>"
+	@echo "  PREFIX    | path | system tree prefix             | '/usr'"
+	@echo "  SHARE_DIR | path | shared data location           | '\$$(DESTDIR)\$$(PREFIX)/share'"
+	@echo "  LIB_DIR   | path | system libraries location      | '\$$(DESTDIR)\$$(PREFIX)/lib'"
+	@echo "  PKGNAME   | name | name of the ditributed package | 'grub-btrfs'"
+	@echo "  INITCPIO  | bool | include mkinitcpio hook        | false"
+	@echo "  SYSTEMD   | bool | include unit files             | true"
+	@echo "  OPENRC    | bool | include OpenRc daemon          | false"
+	@echo

README.md

@@ -5,11 +5,11 @@
 
 This is a version 4.xx of grub-btrfs
 ##### BTC donation address: `1Lbvz244WA8xbpHek9W2Y12cakM6rDe5Rt`
-##
+- - -
-### Description
+### Description :
 Improves Grub by adding "btrfs snapshots" to the Grub menu.
 
-You can start your system on a "snapshot" from the Grub menu.  
+You can boot your system on a "snapshot" from the Grub menu.  
 Supports manual snapshots, snapper, timeshift ...
 
 ##### Warning: booting on read-only snapshots can be tricky
@@ -19,57 +19,138 @@ Otherwise, make sure your snapshots are writeable.
 See [this ticket](https://github.com/Antynea/grub-btrfs/issues/92) for more info.
 
 This project includes its own solution.  
-Refer to the [documentation](https://github.com/Antynea/grub-btrfs/blob/master/initramfs/readme.md).
+* Refer to the [documentation](https://github.com/Antynea/grub-btrfs/blob/master/initramfs/readme.md).  
-
+* Or used `GRUB_BTRFS_SYSTEMD_VOLATILE=true` in config file. (experimental, See [config file](https://github.com/Antynea/grub-btrfs/blob/master/config) for more information.)
-##
+- - -
 ### What does grub-btrfs v4.xx do :
 * Automatically List snapshots existing on root partition (btrfs).
 * Automatically Detect if "/boot" is in separate partition.
 * Automatically Detect kernel, initramfs and intel/amd microcode in "/boot" directory on snapshots.
 * Automatically Create corresponding "menuentry" in `grub.cfg`
-* Automatically detect snapper and use snapper's snapshot description if available.
+* Automatically detect the type/tags and descriptions/comments of snapper/timeshift snapshots.
 * Automatically generate `grub.cfg` if you use the provided systemd service.
 
-##
+- - -
 ### Installation :
 #### Arch Linux
-
+The package is available in the community repository [grub-btrfs](https://archlinux.org/packages/community/any/grub-btrfs/)
 ```
 pacman -S grub-btrfs
 ```
 
+#### Gentoo
+grub-btrfs is only available in the Gentoo User Repository (GURU) and not in the official Gentoo repository.  
+If you have not activated the GURU yet, do so by running:
+```
+emerge -av app-eselect/eselect-repository 
+eselect repository enable guru 
+emerge --sync 
+```
+
+Now merge grub-btrfs via 
+`emerge app-backup/grub-btrfs`
+
 #### Manual
-
 * Run `make install` or look into Makefile for instructions on where to put each file.
+* Run `make help` to check what options are available.
+* Dependencies:
+  * [btrfs-progs](https://archlinux.org/packages/core/x86_64/btrfs-progs/)
+  * [grub](https://archlinux.org/packages/core/x86_64/grub/)
+  * [bash >4](https://archlinux.org/packages/core/x86_64/bash/)
+  * [gawk ](https://archlinux.org/packages/core/x86_64/gawk/)
+  * [strings](https://archlinux.org/packages/core/x86_64/binutils/)
 
-NOTE: Generate your Grub menu after installation for the changes to take effect.  
+#### NOTE: All distros
-On Arch Linux use `grub-mkconfig -o /boot/grub/grub.cfg`.
+Generate your Grub menu after installation for the changes to take effect.  
-
+For example:  
-##
+On **Arch Linux** or **Gentoo** use `grub-mkconfig -o /boot/grub/grub.cfg`.  
-### Customization:
+On **Fedora** use `grub2-mkconfig -o /boot/grub2/grub.cfg`  
+On **Debian-like** distribution `update-grub` is an alias to `grub-mkconfig ...`
+- - -
+### Customization :
 
 You have the possibility to modify many parameters in `/etc/default/grub-btrfs/config`.  
 See [config file](https://github.com/Antynea/grub-btrfs/blob/master/config) for more information.
 
-##
+- - -
-### Automatically update grub
+### Automatically update grub :
-If you would like Grub to automatically update when a snapshot is made or deleted:
+#### Systemd
-* Use `systemctl start/enable grub-btrfs.path`.
+1. If you would like grub-btrfs menu to automatically update when a snapshot is created or deleted:
-* `grub-btrfs.path` automatically (re)generates `grub.cfg` when a modification appears in `/.snapshots` folder (by default).
+* Use `systemctl enable grub-btrfs.path`.
-* If your snapshots aren't mounted in `/.snapshots`, you must modify the watch folder using `systemctl edit grub-btrfs.path`.  
+  * `grub-btrfs.path` automatically (re)generates `grub-btrfs.cfg` when a modification appears in `/.snapshots` mount point (by default).
-	* For example: Timeshift mount its snapshots in `/run/timeshift/backup/timeshift-btrfs/snapshots` folder.
+  * If the `/.snapshots` mount point is already mounted, then use `systemctl start grub-btrfs.path` to start monitoring.  
+    Otherwise, the unit will automatically start monitoring when the mount point will be available.
+* If your snapshots location aren't mounted in `/.snapshots`, you must modify `grub-btrfs.path` unit using  
+`systemctl edit --full grub-btrfs.path` and run `systemctl reenable grub-btrfs.path` for changes take effect.  
+To find out the name of the `.mount` unit  
+use `systemctl list-units -t mount`.  
+	* For example: Timeshift mounts its snapshot folder in `/run/timeshift/backup/timeshift-btrfs/snapshots`.
 
-		Use `systemctl edit grub-btrfs.path`.
+		Use `systemctl edit --full grub-btrfs.path`.
-		Then wrote:
+		Then replace the whole block by:
 		```
+		[Unit]
+		Description=Monitors for new snapshots
+		DefaultDependencies=no
+		Requires=run-timeshift-backup.mount
+		After=run-timeshift-backup.mount
+		BindsTo=run-timeshift-backup.mount
+
 		[Path]
 		PathModified=/run/timeshift/backup/timeshift-btrfs/snapshots
+
+		[Install]
+		WantedBy=run-timeshift-backup.mount
 		```
-		and finally save.
+		Then save and finally run `systemctl reenable grub-btrfs.path` for changes take effect.  
+		Optional:  
+		If the `/run/timeshift/backup/timeshift-btrfs/snapshots` mount point is already mounted,  
+		then use `systemctl start grub-btrfs.path` to start monitoring.  
+		Otherwise, the unit will automatically start monitoring when the mount point will be available.  
 	* You can view your change to `systemctl cat grub-btrfs.path`.
 	* To revert change use `systemctl revert grub-btrfs.path`.
+
+2. If you would like grub-btrfs menu to automatically update on system restart/ shutdown:  
+[Look at this comment](https://github.com/Antynea/grub-btrfs/issues/138#issuecomment-766918328)  
+Currently not implemented
 ##
+#### OpenRC
+1. If you would like grub-btrfs menu to automatically update when a snapshot is created or deleted:
+* Use `rc-config add grub-btrfsd default`, to start the grub-btrfsd daemon the next time the system boots. 
+	* To start `grub-btrfsd` right now, run `rc-service grub-btrfsd start`
+	* `grub-btrfsd` automatically watches the snapshot directory of timeshift (/run/timeshift/backup/timeshift-btrfs/snapshots)
+	and updates the grub-menu when a change occurs.
+* Currently untested for snapper
+
+2. If you would like grub-btrfs menu to automatically update on system restart/ shutdown:
+Just add the following script as `/etc/local.d/grub-btrfs-update.stop`
+	```
+	#!/bin/bash
+	
+	description="Update the grub btrfs snapshots menu"
+	name="grub-btrfs-update"
+	
+	depend()
+	{
+	  use localmount
+	}
+	
+	bash -c 'if [ -s "${GRUB_BTRFS_GRUB_DIRNAME:-/boot/grub}/grub-btrfs.cfg" ]; then /etc/grub.d/41_snapshots-btrfs; else {GRUB_BTRFS_MKCONFIG:-grub-mkconfig} -o {GRUB_BTRFS_GRUB_DIRNAME:-/boot/grub}/grub.cfg; fi' 
+	```
+	
+	Make your script executeable with `chmod a+x /etc/local.d/grub-btrfs-update.stop`.
+
+* The extension ".stop" at the end of the filename indicates to locald that this script should be run at shutdown. 
+ If you want to run the menu update on startup instead, rename the file to `grub-btrfs-update.start`
+* Works for snapper and timeshift
+
+##### Warning :
+by default, `grub-mkconfig` command is used.  
+Might be `grub2-mkconfig` on some systems (Fedora ...).   
+Edit `GRUB_BTRFS_MKCONFIG` variable in `/etc/default/grub-btrfs/config` file to reflect this.
+- - -
 ### Special thanks for assistance and contributions
-* [maximbaz](https://github.com/maximbaz)
+* [Maxim Baz](https://github.com/maximbaz)
+* [Schievel1](https://github.com/Antynea/grub-btrfs/discussions/173#discussioncomment-1438790)
 * [All contributors](https://github.com/Antynea/grub-btrfs/graphs/contributors)
-##
+- - -

config

@@ -8,18 +8,10 @@
 # Default: "Use distribution information from /etc/os-release."
 #GRUB_BTRFS_SUBMENUNAME="Arch Linux snapshots"
 
-# Add a name ahead your snapshots entries in the Grub menu.
-# Default: "Snapshot:"
-#GRUB_BTRFS_PREFIXENTRY="Snapshot:"
-
-# Show full path snapshot or only name in the Grub menu, weird reaction with snapper.
-# Default: "true"
-#GRUB_BTRFS_DISPLAY_PATH_SNAPSHOT="false"
-
 # Custom title.
-# shows/hides p"prefix" d"date" n"name" in the Grub menu, separator "/", custom order available.
+# Shows/Hides "date" "snapshot" "type" "description" in the Grub menu, custom order available.
-# Default: "p/d/n"
+# Default: ("date" "snapshot" "type" "description")
-#GRUB_BTRFS_TITLE_FORMAT="p/d/n"
+#GRUB_BTRFS_TITLE_FORMAT=("date" "snapshot" "type" "description")
 
 # Limit the number of snapshots populated in the GRUB menu.
 # Default: "50"
@@ -54,6 +46,24 @@
 # Default: ("")
 #GRUB_BTRFS_CUSTOM_MICROCODE=("custom-ucode.img" "custom-uc.img "custom_ucode.cpio")
 
+# Comma seperated mount options to be used when booting a snapshot.
+# They can be defined here as well as in the "/" line inside the respective snapshots'
+# "/etc/fstab" files.  Mount options found in both places are combined, and this variable
+# takes priority over `fstab` entries.
+# NB: Do NOT include "subvol=..." or "subvolid=..." here.
+# Default: ""
+#GRUB_BTRFS_ROOTFLAGS="space_cache,commit=10,norecovery"
+
+# Booting on read-only snapshots can be tricky. (See https://github.com/Antynea/grub-btrfs#warning-booting-on-read-only-snapshots-can-be-tricky)
+# Based on several reports, "/var" must be writable to start properly.
+# Systemd can do this for you. (not compatible with OpenRC)
+# The snapshot will boot in read-only mode but "/var" will be writable using a "tmpfs" mount point (which means, folder mounted in RAM)
+# This should make it easier to rollback.
+# Note to all: Detecting "systemd" as the default init on the snapshot is automatic, if don't, file a bug report at https://github.com/Antynea/grub-btrfs.
+# Note to Arch Linux users: If you use the "grub-btrfs-overlayfs" option on Arch Linux, "GRUB_BTRFS_SYSTEMD_VOLATILE" will do nothing.
+# Default: "false"
+#GRUB_BTRFS_SYSTEMD_VOLATILE=true
+
 # Ignore specific path during run "grub-mkconfig".
 # Only exact paths are ignored.
 # e.g : if `specific path` = @, only `@` snapshot will be ignored.
@@ -66,10 +76,22 @@ GRUB_BTRFS_IGNORE_SPECIFIC_PATH=("@")
 # Default: ("var/lib/docker" "@var/lib/docker" "@/var/lib/docker")
 GRUB_BTRFS_IGNORE_PREFIX_PATH=("var/lib/docker" "@var/lib/docker" "@/var/lib/docker")
 
+# Ignore specific type/tag of snapshot during run "grub-mkconfig".
+# For snapper:
+# Type = single, pre, post.
+# For Timeshift:
+# Tag = boot, ondemand, hourly, daily, weekly, monthly.
+# Default: ("")
+#GRUB_BTRFS_IGNORE_SNAPSHOT_TYPE=("")
+
+# Ignore specific description of snapshot during run "grub-mkconfig".
+# e.g: timeline
+# Default: ("")
+#GRUB_BTRFS_IGNORE_SNAPSHOT_DESCRIPTION=("")
+
 # By default "grub-btrfs" automatically detects your boot partition,
-# either located at the system root or on a separate partition,
+# either located at the system root or on a separate partition or in a subvolume,
-# but cannot detect if it is in a subvolume.
+# Change to "true" if your boot partition isn't detected as separate.
-# Change to "true" if you have a boot partition in a different subvolume.
 # Default: "false"
 #GRUB_BTRFS_OVERRIDE_BOOT_PARTITION_DETECTION="true"
 
@@ -85,16 +107,25 @@ GRUB_BTRFS_IGNORE_PREFIX_PATH=("var/lib/docker" "@var/lib/docker" "@/var/lib/doc
 # Default: "/boot"
 #GRUB_BTRFS_BOOT_DIRNAME="/boot"
 
-# Name/path of grub-mkconfig, use by "grub-btrfs.service"
+# Name/path of grub-mkconfig command, use by "grub-btrfs.service"
-# Might be 'grub2-mkconfig' on some systems
+# Might be 'grub2-mkconfig' on some systems (Fedora ...)
+# Default paths are /sbin:/bin:/usr/sbin:/usr/bin,
+# if your path is missing, report it on the upstream project.
 # For example, on Fedora : "/sbin/grub2-mkconfig"
-# Default: /usr/bin/grub-mkconfig
+# You can use only name or full path.
+# Default: grub-mkconfig
 #GRUB_BTRFS_MKCONFIG=/usr/bin/grub2-mkconfig
 
-# Snapper
+# Name of grub-script-check command, use by "grub-btrfs"
-# Snapper's config name to use
+# Might be 'grub2-script-check' on some systems (Fedora ...)
-# Default: "root"
+# For example, on Fedora : "grub2-script-check"
-#GRUB_BTRFS_SNAPPER_CONFIG="root"
+# Default: grub-script-check
+#GRUB_BTRFS_SCRIPT_CHECK=grub2-script-check
+
+# Path of grub-mkconfig_lib file, use by "grub-btrfs"
+# Might be '/usr/share/grub2/grub-mkconfig_lib' on some systems (Opensuse ...)
+# Default: /usr/share/grub/grub-mkconfig_lib
+#GRUB_BTRFS_MKCONFIG_LIB=/usr/share/grub2/grub-mkconfig_lib
 
 # Password protection management for submenu,snapshots
 # Refer to the Grub documentation https://www.gnu.org/software/grub/manual/grub/grub.html#Authentication-and-authorisation

grub-btrfs-openrc

@@ -0,0 +1,6 @@
+#!/bin/sh
+echo $$ > /run/grub-btrfsd.pid
+
+while true; do sleep 1 && inotifywait -e create -e delete /run/timeshift/backup/timeshift-btrfs/snapshots && sleep 5 && if [ -s "${GRUB_BTRFS_GRUB_DIRNAME:-/boot/grub}/grub-btrfs.cfg" ]; then /etc/grub.d/41_snapshots-btrfs; else ${GRUB_BTRFS_MKCONFIG:-grub-mkconfig} -o ${GRUB_BTRFS_GRUB_DIRNAME:-/boot/grub}/grub.cfg; fi  ; done
+
+

grub-btrfs.path

@@ -1,8 +1,12 @@
 [Unit]
 Description=Monitors for new snapshots
+DefaultDependencies=no
+Requires=\x2esnapshots.mount
+After=\x2esnapshots.mount
+BindsTo=\x2esnapshots.mount
 
 [Path]
 PathModified=/.snapshots
 
 [Install]
-WantedBy=multi-user.target
+WantedBy=\x2esnapshots.mount

grub-btrfs.service

@@ -8,4 +8,4 @@ Environment="PATH=/sbin:/bin:/usr/sbin:/usr/bin"
 # Load environment variables from the configuration
 EnvironmentFile=/etc/default/grub-btrfs/config
 # Regenerate just '/boot/grub/grub-btrfs.cfg' if it exists and is not empty, else regenerate the whole grub menu
-ExecStart=/bin/bash -c 'if [ -s "${GRUB_BTRFS_GRUB_DIRNAME:-/boot/grub}/grub-btrfs.cfg" ]; then /etc/grub.d/41_snapshots-btrfs; else ${GRUB_BTRFS_MKCONFIG:-/usr/bin/grub-mkconfig} -o ${GRUB_BTRFS_GRUB_DIRNAME:-/boot/grub}/grub.cfg; fi' 
+ExecStart=bash -c 'if [ -s "${GRUB_BTRFS_GRUB_DIRNAME:-/boot/grub}/grub-btrfs.cfg" ]; then /etc/grub.d/41_snapshots-btrfs; else ${GRUB_BTRFS_MKCONFIG:-grub-mkconfig} -o ${GRUB_BTRFS_GRUB_DIRNAME:-/boot/grub}/grub.cfg; fi' 

grub-btrfsd

@@ -0,0 +1,14 @@
+#!/sbin/openrc-run
+# Copyright 1999-2021 Gentoo Foundation
+# Distributed under the terms of the GNU General Public License v2
+
+name="grub-btrfs daemon"
+command="/usr/bin/grub-btrfs-openrc"
+pidfile="/run/{RC_SVCNAME}.pid"
+command_background=true
+
+depend() {
+   use localmount
+}
+
+