r2w.sh

echo "Scanning GRUB ..."
sudo grub-mkconfig > /tmp/grub_config.tmp 2>&1
menu=$(grep -E '^(menuentry|submenu)' /tmp/grub_config.tmp)
echo "\n### GRUB boot menu ###"
#echo "$menu"
num=$(echo "$menu" | wc -l)
for i in $(seq 1 $(($num)))
do
    line=$(echo "$menu" | sed -n "${i}p")
    name=$(echo "$line" | grep -o "'[^']*'" | head -n 1 | cut -c 2- | rev | cut -c 2- | rev)
    echo "$i: $name"
done
rm /tmp/grub_config.tmp
case $# in
0) 
    echo "\nSelect the index of the target system:"
    read target_index
    ;;
1) 
    target_index=$1
    ;;
*)
    echo "usage: r2w [sys]"
    exit
esac
if [ $target_index -gt 0 ] && [ $target_index -le $num ] 2>/dev/null ;
then 
    line=$(echo "$menu" | sed -n "${target_index}p")
    name=$(echo "$line" | grep -o "'[^']*'" | head -n 1 | cut -c 2- | rev | cut -c 2- | rev)
    echo "Selected system: ${name}"
    sudo grub-reboot $((target_index - 1))
    sudo reboot
else 
    echo "$target_index is invalid."
fi