How to create a user with a strong password using Bash Script

It's been a long time I documented how I accomplished a task and I have decided to change that going forward so help me God. I am picking up my hypothetical pen again to face the world of automation heads on 🚀.

Today, I'm going to walk you through how I created a user with a strong password using bash script. This code can be used to create users in a school or work system or any Linux system where you need users and passwords .

Using Bashcript will help automate the process so you don't have to run multiple commands every time you have to create a new user.

A basic knowledge of Bash-scripting is required to understand what I did as I didn't exactly break down the concepts in bits.

For this task, I customized the code to fit a school system, but you can totally change it to fit your scenario with just a few echos 😉

Steps

First we write a function to confirm that the username is avaliable

#!/bin/bash 
echo "Welcome to Laurel's High School!"
echo "Kindly create your account"

read -p "Enter a username: " username
# Check if the username is already taken
function check_username {
  useradd -n $1 >/dev/null 2>&1
  if [ $? -eq 0 ]; then
    echo "Username '$1' is already taken. Please choose a different username."
    return 1
  fi
}
check_username $username

Then we prompt our user for password ensuring they reconfirm the password

# prompt for password
echo "Password must be at least 8 characters long and include an uppercase, lowercase, number and special characters): "
echo "Enter a strong password(hidden):"
read -s password

echo "Confirm your password match: "
read -s password2

Then we set our conditions ensuring that the password is strong and meets the requirements of a mix of uppercase, lowercase, numbers, and special characters.

# Define and ensure password condtions are met 

# Check password match
if [[ $password != $password2 ]]; then
  echo -e $WARNING"Password does not match."$CLEAR
else
  echo -e $SUCCESS"Password matches."$CLEAR
fi 

# check for length
if [[ ${#password} -ge 8 ]]; then
  echo -e $SUCCESS"+Password length is good."$CLEAR
else
  echo -e $WARNING"-Password must be at least 8 characters long."$CLEAR
fi

#check for special characters
if [[ $password =~ [[:punct:]] ]]; then
  echo -e $SUCCESS"+Password has a special character."$CLEAR
else
  echo -e $WARNING"-Password must include at least one special character (!@#$%^&*()+)."$CLEAR
fi

#check for upper and lower case letters
if [[ $password =~ [[:upper:]] && $password =~ [[:lower:]] ]]; then
  echo -e $SUCCESS"+Password contains both uppercase and lowercase letters."$CLEAR
else
  echo -e $WARNING"-Password should contain both uppercase and lowercase letters."$CLEAR
fi

# check for digits
if [[ $password =~ [[:digit:]] ]]; then
  echo -e $SUCCESS"+Password contains at least one digit."$CLEAR
else
  echo -e $WARNING"-Password should contain at least one digit."$CLEAR
fi

Then we validate all our conditions in a function before we confirm password as successful and account creation confirmed.

function validate_password {
  if [[ ${#password} -ge 8 && "$password" =~ [[:punct:]] && $password =~ [[:upper:]] && $password =~ [[:lower:]] && $password =~ [[:digit:]] && $password == $password2 ]]; then
    echo -e "$SUCCESS Password is strong!"$CLEAR
    # Create user with username and hashed password
    sudo useradd -m "$username" -p "$hashed_password"
    echo "Account created successfully!"
    echo -e "Username: $username"
    echo -e "User ID: $(id -u "$username")"
  else
    echo -e "$WARNING Error creating password. kindly comply with the requirements"$CLEAR
  fi
}
validate_password $password

We used the variables below to add colours to our outputs 31 is for red, 32 green, and 33 gold/yellow. Declare the variable at the top of the script

#!/bin/bash
WARNING="\e[31m"
SUCCESS="\e[32m"
CLEAR="\e[1;33m"

Save your script with the .sh extention for bash eg create-user.sh, and run on a linux server withthe command

bash create-user.sh

Also you can make your file executable by running the chmod command to make your file executable and run the command

./ create-user.sh

You can get the complete %[https://github.com/EjiroLaurelD/SCA-Devops/blob/main/linux/create-user.sh]

I hope this helps someone 🙂

Thank you for reading