Write a shell script that greets the user by saying Good Morning, Good Afternoon, and Good Evening according to the system time

d=`date|cut -d " " -f 4|cut -d ":" -f 1`

if [ $d -gt 4 -a $d -lt 12 ]

then

echo Good Morning

elif [ $d -gt 12 -a $d -lt 16 ]

then

echo Good Afternoon

elif [ $d -gt 16 -a $d -lt 20 ]

then

echo Good Evening

else

echo Good Night

fi