Shell Script for User Management

Create & Delete Users on Linux using Bash

Managing users manually on a Linux system can be time-consuming. Let’s make it faster and more consistent with two easy shell scripts:

✅ One to create users
✅ One to delete users

We'll add error handling, secure password input, and clean prompts — all in one simple guide!

Script 1: create_user.sh — Create a New User

💡 What This Script Does:

• Takes username and password as input

• Checks if the user already exists

• If not, creates the user securely

• Handles errors gracefully

📜 Script:

#!/bin/bash
#########################
# Author: Anju
# Date: 12/4/2025
# version: V1
#Write a shell script to create a user
########################################
read -p "Please enter the username: " username #with this command we can take user input from user
read -s -p "Please enter the password: " password # read -s hides the password input
echo  # Just moves to a new line after hidden password input

## with this we can check if user already exit or not.

if id "$username" &>/dev/null; then
        echo "user already exist"
        exit 1 #stops the script right there and signals that something went wrong
else
        #Encrypt the password
        encrypted_pass=$(openssl passwd -1 "$password")

        #Create the user with home directory and encrypted password
        sudo useradd -m "$username" -p "$encrypted_pass"

        # Check if the user was created successfully
        if [ $? -eq 0 ]; then
                        echo "$username user created successfully"
                else
                                echo "error: failed to create user, kindly check again"
        fi

fi

Key points

• Password handling:

  • useradd does not accept plain-text passwords safely.

  • You must encrypt the password using openssl passwd or similar.

  • Password encryption:

      encrypted_pass=$(openssl passwd -1 "$password")
    

💡 What this does:

This line:

1. Takes the user's plain-text password

2. Encrypts (hashes) it

3. Stores the encrypted version in a variable called encrypted_pass

Breaking down the components:

• Security best practice:

  • read -s hides the password input.

  • Avoid printing or echoing sensitive information like passwords.

• Check if the user already exists before creating

    if id "$username" &>/dev/null; then
            echo "user already exist"
            exit 1
    fi
  

  Purpose: This command checks whether a user with the username stored in the variable $username already exists on the system.

  Component Breakdown:

  | Part | Meaning | | --- | --- |

  id	This is a command that displays the user ID (uid) and group ID (gid) of a specified username.

  "$username"

  This passes the value of the username variable to the id command. Using double quotes is good practice in case the variable contains spaces or special characters.

  &>/dev/null

  This redirects both standard output (stdout) and standard error (stderr) to /dev/null, which is like a "black hole" — anything sent there is discarded. So this makes the command silent, meaning it won’t print anything on the screen whether the user exists or not.

• Why use exit 1 here?

  • You don’t want the script to continue if the user already exists.

  • So exit 1 stops the script right there and signals that something went wrong (in this case, the user already exists).

  • It's a good way to fail gracefully instead of trying to re-create an existing user, which would cause errors.

If you don't use exit 1, then the script would continue running — and possibly try to run useradd, which will fail since the user already exists. That could cause confusing or messy errors.

Script 2: delete_user.sh — Delete an Existing User

💡 What This Script Does:

• Takes a username to delete

• Checks if the user exists

• Deletes the user and their home directory

• Handles errors if deletion fails

---

📜 Script:

vim delete_user.sh

#!/bin/bash
#########################
# Author: Anju
# Date: 12/4/2025
# version: V1
#Write a shell script to create a user
########################################
read -p "Please enter the username you want to delete: " username #with this command we can take username as input from user
echo "" # for space

if id "$username" &>/dev/null; then
        sudo userdel -r "$username"
        if [ $? -eq 0 ]; then
                echo "user deleted successfully"
        else
                echo "error: try again to delete this user"
        fi
else
        echo "this user does not exist to delete"
fi

all check points

• ✅ Taken user input

• ✅ Checked if the user exists

• ✅ Deleted the user (with their home directory)

• ✅ Handled both success and error cases

see the output

output:

userdel: Shree mail spool (/var/mail/Shree) not found
user deleted successfully

🧠 What it means: userdel tries to delete everything related to the user, including:

Home directory (/home/Shree)

Mail spool file (/var/mail/Shree)

In your case, the mail spool file didn't exist, so it showed a non-fatal warning:

userdel: Shree mail spool (/var/mail/Shree) not found

✅ This is not an error — just a message saying that it didn’t find any mail to delete.

🚀 How to Run These Scripts:

1. Make them executable:

    bashCopyEditchmod +x create_user.sh delete_user.sh
   

2. Run the scripts:

    bashCopyEdit./create_user.sh
    ./delete_user.sh
   

💡 You need sudo privileges to run these commands.

done :)