diff --git a/41_snapshots-btrfs b/41_snapshots-btrfs
index 0dddfec..05736c3 100755
--- a/41_snapshots-btrfs
+++ b/41_snapshots-btrfs
@@ -1,4 +1,4 @@
-#! /usr/bin/env bash
+#! /usr/bin/env sh
 #
 # Written by: Antynea
 # BTC donation address: 1Lbvz244WA8xbpHek9W2Y12cakM6rDe5Rt
@@ -41,14 +41,16 @@ set -e
 sysconfdir="/etc"
 grub_btrfs_config="${sysconfdir}/default/grub-btrfs/config"
 
+# shellcheck disable=SC1090
 [ -f "$grub_btrfs_config" ] && . "$grub_btrfs_config"
+# shellcheck disable=SC1091
 [ -f "${sysconfdir}/default/grub" ] && . "${sysconfdir}/default/grub"
 
 ## Error Handling
 print_error()
 {
-    local err_msg="$*"
-    local bug_report="If you think an error has occurred, please file a bug report at \"https://github.com/Antynea/grub-btrfs\""
+    err_msg="$*"
+    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
 }
@@ -77,8 +79,10 @@ done
 ## Exit the script, if:
 [ "$(echo "$GRUB_BTRFS_DISABLE" | tr '[:upper:]' '[:lower:]')" = 'true' ] && print_error "GRUB_BTRFS_DISABLE is set to true (default=false)"
 if ! type btrfs >/dev/null 2>&1; then print_error "btrfs-progs isn't installed"; fi
+# shellcheck disable=SC1090,SC2015
 [ -f "${GRUB_BTRFS_MKCONFIG_LIB:-/usr/share/grub/grub-mkconfig_lib}" ] && . "${GRUB_BTRFS_MKCONFIG_LIB:-/usr/share/grub/grub-mkconfig_lib}" || print_error "grub-mkconfig_lib couldn't be found"
-[[ "$(btrfs filesystem df / 2>&1)" == *"not a btrfs filesystem"* ]] && print_error "Root filesystem isn't btrfs"
+# shellcheck disable=SC2005
+if echo "$(btrfs filesystem df / 2>&1)" | grep "not a btrfs filesystem" >/dev/null 2>&1; then print_error "Root filesystem isn't btrfs"; fi
 
 printf "Detecting snapshots ...\n" >&2 ;
 
@@ -110,16 +114,28 @@ fi
 
 ## Probe information of Root and Boot devices
 # Probe info "Root partition"
+# shellcheck disable=SC2154 # grub_probe is provided by grub environment
 root_device=$(${grub_probe} --target=device /) # Root device
+# shellcheck disable=SC2086 # we actually need word splitting here if we have several root devices (e.g. RAID)
 root_uuid=$(${grub_probe} --device ${root_device} --target="fs_uuid" 2>/dev/null) # UUID of the root device
 root_uuid_subvolume=$(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
-root_uuid_subvolume=$(awk -F":" 'match($1, /(^[ \t]+UUID)/) {sub(/^[ \t]+/, "", $2); print $2}' <<< "$root_uuid_subvolume") # UUID of the root subvolume '
+root_uuid_subvolume=$(awk -F":" 'match($1, /(^[ \t]+UUID)/) {sub(/^[ \t]+/, "", $2); print $2}' <<EOF
+"$root_uuid_subvolume"
+EOF
+) # UUID of the root subvolume '
 # Probe info "Boot partition"
+# shellcheck disable=SC2086 # we actually need word splitting here if we have several devices
 boot_device=$(${grub_probe} --target=device ${boot_directory}) # Boot device
+# shellcheck disable=SC2086 # we actually need word splitting here if we have several devices
 boot_uuid=$(${grub_probe} --device ${boot_device} --target="fs_uuid" 2>/dev/null) # UUID of the boot device
 boot_uuid_subvolume=$(btrfs subvolume show "$boot_directory" 2>/dev/null) || boot_uuid_subvolume=" UUID: $root_uuid_subvolume"; # If boot folder isn't a subvolume, then UUID=root_uuid_subvolume
-boot_uuid_subvolume=$(awk -F":" 'match($1, /(^[ \t]+UUID)/) {sub(/^[ \t]+/, "", $2); print $2}' <<< "$boot_uuid_subvolume") # UUID of the boot subvolume '
+boot_uuid_subvolume=$(awk -F":" 'match($1, /(^[ \t]+UUID)/) {sub(/^[ \t]+/, "", $2); print $2}' <<EOF
+"$boot_uuid_subvolume"
+EOF
+) # UUID of the boot subvolume '
+# shellcheck disable=SC2086 # we actually need word splitting here if we have several devices
 boot_hs=$(${grub_probe} --device ${boot_device} --target="hints_string" 2>/dev/null) # hints string
+# shellcheck disable=SC2086 # we actually need word splitting here if we have several devices
 boot_fs=$(${grub_probe} --device ${boot_device} --target="fs" 2>/dev/null) # Type filesystem of boot device
 
 ## Parameters passed to the kernel
@@ -143,7 +159,7 @@ fi
 ## Detect rootflags
 detect_rootflags()
 {
-    local fstabflags=$(grep -oE '^\s*[^#][[:graph:]]+\s+/\s+btrfs\s+[[:graph:]]+' "${grub_btrfs_mount_point}/${snap_dir_name_trim}/etc/fstab" \
+    fstabflags=$(grep -oE '^\s*[^#][[:graph:]]+\s+/\s+btrfs\s+[[:graph:]]+' "${grub_btrfs_mount_point}/${snap_dir_name_trim}/etc/fstab" \
                         | sed -E 's/^.*[[:space:]]([[:graph:]]+)$/\1/;s/,?subvol(id)?=[^,$]+//g;s/^,//')
     rootflags="rootflags=${fstabflags:+$fstabflags,}${GRUB_BTRFS_ROOTFLAGS:+$GRUB_BTRFS_ROOTFLAGS,}"
 }
@@ -151,8 +167,8 @@ detect_rootflags()
 unmount_grub_btrfs_mount_point()
 {
 if [ -d "$grub_btrfs_mount_point" ]; then
-    local wait=true
-    local wait_max=0
+    wait=true
+    wait_max=0
     printf "Unmount %s .." "$grub_btrfs_mount_point" >&2;
     while $wait; do
         if grep -qs "$grub_btrfs_mount_point" /proc/mounts; then
@@ -200,6 +216,7 @@ make_menu_entries()
                 # prefix_i=${i%%"-"*}
                 suffix_i=${i#*"-"}
                 # alt_suffix_i=${i##*"-"}
+                # shellcheck disable=SC2269 # this is a way to exit the if..elif..
                 if   [ "${kversion}" = "${suffix_i}" ];                 then i="${i}";
                 elif [ "${kversion}.img" = "${suffix_i}" ];             then i="${i}";
                 elif [ "${kversion}-fallback.img" = "${suffix_i}" ];    then i="${i}";
@@ -279,21 +296,21 @@ make_menu_entries()
 
 ## Trim a string from leading and trailing whitespaces
 trim() {
-    local var="$*"
+    var="$*"
     var="${var#"${var%%[![:space:]]*}"}"
     var="${var%"${var##*[![:space:]]}"}"
-    echo -n "$var"
+    printf '%s' "$var"
 }
 
 ## List of snapshots on filesystem
 snapshot_list()
 {
-    local snapper_info="info.xml"
-    local timeshift_info="info.json"
-    local date_snapshots=()
-    local path_snapshots=()
-    local type_snapshots=()
-    local description_snapshots=()
+    snapper_info="info.xml"
+    timeshift_info="info.json"
+    date_snapshots=()
+    path_snapshots=()
+    type_snapshots=()
+    description_snapshots=()
     IFS=$'\n'
     for snap in $(btrfs subvolume list -sa "${btrfs_subvolume_sort}" /); do # Parse btrfs snapshots
         IFS=$oldIFS
@@ -320,7 +337,8 @@ snapshot_list()
         local description_snapshot="N/A"
         
         # path to yabsnap snapshot meta data
-        local yabsnap_info="$grub_btrfs_mount_point/${path_snapshot%"/"*}/$(echo "${snap[13]}" | awk -F'/' '{print $3 "-meta.json"}')"
+        local yabsnap_info
+        yabsnap_info="$grub_btrfs_mount_point/${path_snapshot%"/"*}/$(echo "${snap[13]}" | awk -F'/' '{print $3 "-meta.json"}')"
 
         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"
@@ -399,30 +417,31 @@ parse_snapshot_list()
 
     snap_dir_name="$(echo "$item" | cut -d'|' -f2)" # column_2
     snap_dir_name_trim="$(trim "$snap_dir_name")"
-    snap_snapshot="$snap_dir_name" # Used by "title_format" function
-
+    # shellcheck disable=SC2034 # Used by "title_format" function
+    snap_snapshot="$snap_dir_name"
+    # shellcheck disable=SC2034 # Used by "title_format" function
     snap_type="$(echo "$item" | cut -d'|' -f3)" # column_3
-
+    # shellcheck disable=SC2034 # Used by "title_format" function
     snap_description="$(echo "$item" | cut -d'|' -f4)" # column_4
 }
 
 ## Detect kernels in "boot_directory"
 detect_kernel()
 {
-    list_kernel=()
+    list_kernel=""
     # Original kernel (auto-detect)
     for okernel in  "${boot_dir}"/vmlinuz-* \
                     "${boot_dir}"/vmlinux-* \
                     "${boot_dir}"/kernel-* ; do
         [ ! -f "${okernel}" ] && continue;
-        list_kernel+=("$okernel")
+        list_kernel="${list_kernel} $okernel"
     done
 
     # Custom name kernel in "GRUB_BTRFS_NKERNEL"
     if [ -n "${GRUB_BTRFS_NKERNEL}" ] ; then
-        for ckernel in "${boot_dir}/${GRUB_BTRFS_NKERNEL[@]}" ; do
+        for ckernel in "${boot_dir}"/${GRUB_BTRFS_NKERNEL} ; do
             [ ! -f "${ckernel}" ] && continue;
-            list_kernel+=("$ckernel")
+            list_kernel="${list_kernel} $okernel"
         done
     fi
 }
@@ -468,7 +487,7 @@ detect_microcode()
     # Custom name microcode in "GRUB_BTRFS_CUSTOM_MICROCODE"
     if [ -n "${GRUB_BTRFS_CUSTOM_MICROCODE}" ] ; then
         for cucode in "${boot_dir}/${GRUB_BTRFS_CUSTOM_MICROCODE[@]}" ; do
-            [[ ! -f "${cucode}" ]] && continue
+            [ ! -f "${cucode}" ] && continue
             list_ucode+=("$cucode")
         done
     fi
@@ -481,7 +500,7 @@ title_format()
 {
     title_menu="|" # "|" is for visuals only
     title_submenu="|" # "|" is for visuals only
-    [[ -z "${GRUB_BTRFS_TITLE_FORMAT}" ]] && GRUB_BTRFS_TITLE_FORMAT=("date" "snapshot" "type" "description"); # Default parameters
+    [ -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],,}" # $var is a indirect variable
@@ -496,15 +515,15 @@ title_format()
 # Adds a header to the grub-btrfs.cfg file
 header_menu()
 {
-    local header_entry=""
-    [[ -z "${GRUB_BTRFS_TITLE_FORMAT}" ]] && GRUB_BTRFS_TITLE_FORMAT=("date" "snapshot" "type" "description"); # Default parameters
+    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[$key],,}]})));
+            lenght_title_column_left=$(((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[$key],,}]}" "|") # Final "|" is for visuals only
         done
@@ -523,6 +542,7 @@ boot_bounded()
         boot_dir="$grub_btrfs_mount_point/$snap_dir_name_trim$boot_directory"
         detect_kernel
         if [ -z "${list_kernel}" ]; then continue; fi
+        # TODO
         name_kernel=("${list_kernel[@]##*"/"}")
         detect_initramfs
         name_initramfs=("${list_initramfs[@]##*"/"}")
@@ -614,6 +634,7 @@ if [ "${count_limit_snap}" = "0" ] || [ -z "${count_limit_snap}" ]; then
 fi
 # Move "grub-btrfs.new" to "grub-btrfs.cfg"
 header_menu
+# shellcheck disable=SC2154 # bindir is provided by grub environment
 if "${bindir}/${GRUB_BTRFS_SCRIPT_CHECK:-grub-script-check}" "$grub_btrfs_directory/grub-btrfs.new"; then
     cat "$grub_btrfs_directory/grub-btrfs.new" > "$grub_btrfs_directory/grub-btrfs.cfg"
     rm -f "$grub_btrfs_directory/grub-btrfs.new" "$grub_btrfs_directory/grub-btrfs.cfg.bkp"
diff --git a/config b/config
index 03f8f4e..2435406 100644
--- a/config
+++ b/config
@@ -1,7 +1,7 @@
 #!/usr/bin/env bash
 
 
-GRUB_BTRFS_VERSION=4.13-yabsnap_info_support-2024-03-06T13:43:57+00:00
+GRUB_BTRFS_VERSION=4.13-fix-bashisms-2024-03-27T20:48:48+00:00
 
 # Disable grub-btrfs.
 # Default: "false"