echo enter time
read t
if [ "$t" -ge 5 ] && [ "$t" -lt 12 ]; then
echo good morning
elif [ "$t" -ge 12 ] && [ "$t" -lt 17 ]; then
echo good afetrnoon
elif [ "$t" -ge 17 ] && [ "$t" -lt 21 ]; then
echo good evening
else
echo good night
fi