Notes

function check(){
getent passwd $username > /dev/null # checking if the name user input already exists or not
if [ $? -eq 0 ]; then # $? is set when you run valid (0) and invalid (1) bash commands.
num=$(( $RANDOM % 9 + 0 ))
username=${username}$num
check $username
else
SUB='Linux'
len=`expr length "$username"`
if [ $len -ge 5 ]; then
echo -e " "
sudo useradd $username #adding the new user with root user permition
#echo "USER $username HAS BEEN CREATED SUCCESSFULLY !"
echo "$username"
echo ""
else
num=$(( $RANDOM % 9 + 0 ))
username=${username}$num
check $username
fi
option # redirecting to the main menu after the process is completed
fi
}

function new_user(){
echo " Enter User First Name : " #instruction
read firstname # user inputs
echo " Enter User Middle Name : " #instruction
read midname # user inputs
echo " Enter User Last Name : " #instruction
read lastname # user inputs

username=$firstname$lastname
check $username

}



function option(){
echo ""
echo "CHOOSE ANY NUMBER FOR THE RESPECTIVE EVENT" #instruction
echo ""
echo "ENTER 1 FOR ADDING A USER " #instruction
echo "ENTER 2 FOR ADDING A GROUP" #instruction
echo "ENTER 3 TO EXIT" #instruction

read choice
if [[ $choice -eq 1 ]]
then
new_user # funciton called for adding a new user
elif [[ $choice -eq 2 ]]; then
new_group # funciton called for adding a new group
elif [[ $choice -eq 3 ]]; then
exit 1
else
echo "Invalid input" #for error view
option # redirecting to the same function to complete the execution
fi
}



echo "~~WELCOME TO THE PROGRAM FOR MODIFICATION OF USERS AND GROUPS~~" #welcome text
echo ""
option