Learn Linux Shell Scripting (The 'until' Loop)

Learn Linux Shell Scripting (The 'until' Loop)
Here is the entire shell script "until_demo.bash" that was demonstrated in this session:
$ cat until_demo.bash
#!/usr/bin/env bash

# Purpose: To demonstrate the 'until' loop
# The until loops as long as the condition is false, exit when
# the condition becomes true
# Author: Wahid Lutfy
# CopyRight: MyWebUnivesity Free Educational Videos

num=5
until [ ${num} -eq 0 ]
do
clear
echo -e "\n\n"
echo -e "\t\t *****************************************************"
echo -e "\t\t * SysAdmin Main Menu *"
echo -e "\t\t * 1: Run the top command *"
echo -e "\t\t * 2: Run the htop command *"
echo -e "\t\t * 3: Run the 'df -h / /usr /home /var /tmp' command *"
echo -e "\t\t * 4: Monitor Apache Web Server Processes *"
echo -e "\t\t * 0: Exit *"
echo -e "\t\t *****************************************************"
echo -e "\t\t Please select a number between 0-4.\c"
read num
if test ${num} -eq 1
then
echo -e "\n\t\tYou selected option 1 to run top command.\n"
top
read key
elif test ${num} -eq 2
then
echo -e "\n\t\tYou selected option 2 to run htop command.\n"
htop
read key
elif test ${num} -eq 3
then
clear
echo -e "\n\tYou selected option 3"
echo -e "\tThe output for 'df -h / /usr /home /var /tmp' is:\n"
df -h / /usr /home /var /tmp
read key
elif test ${num} -eq 4
then
clear
echo -e "\n\tYou selected option 4\n"
echo -e "\tThe output for 'systemctl status apache2' is:\n"
systemctl status apache2
read key
elif test ${num} -eq 0
then
echo -e "\n\t\t You selected option 0 which is to exit."
echo -e "\t\t Thanks for using our SysAdmin Main Menu!\n"
exit
else
echo -e "\t\t\nPlease choose one of the options 0-4 from Main Menu.\n"
fi
done