SpectreOS/configs/grub.d/40_snapshots

#!/bin/sh
. /etc/default/grub
export GRUB_DISABLE_RECOVERY=true
export GRUB_DISABLE_SUBMENU=y
export GRUB_CMDLINE_LINUX_DEFAULT=$GRUB_CMDLINE_LINUX_DEFAULT

if [ -f "/etc/grub-snapshot" ]; then
  if [ "$(cat /etc/grub-snapshot | wc -l)" != 0 ]; then
    # TRANSLATORS: %s is replaced with an OS name
    echo "submenu 'Snapshot options for SpectreOS' \$menuentry_id_option 'gnulinux-snapshot-$boot_device_id' {"
    is_top_level=false
    snapshotanzahl="$(expr $(wc -l /etc/grub-snapshot | awk '{print $1}') + 1)"
    grub_output=$(/etc/grub.d/10_linux)
    while (( "$(expr $snapshotanzahl - 1)" )); do
      snapshotanzahl=`expr ${snapshotanzahl} - 1`
      SNAPSHOTNAME="$(cat /etc/grub-snapshot | sed ''$snapshotanzahl'!d')"
      SNAPSHOT="rootflags=subvol=${SNAPSHOTNAME}"

      export GRUB_CMDLINE_LINUX="${SNAPSHOT} ${GRUB_CMDLINE_LINUX#* }"
      echo "$grub_output" | python /usr/bin/extract-menuentry.py "Snapshot ${SNAPSHOT#*@}"
    done
    echo '}'
  fi
fi