Linux User Creation Bash Script

Hello everyone, I am Kahuna, and I’m excited to share my latest technical article. As a DevOps engineer, I was asked to manage user accounts and groups. Today, I’ll walk you through a script I wrote to automate this process. This script reads a text file containing usernames and their respective groups, creates users and groups as specified.

Prerequisites

I ensured I have the necessary permissions to create users and groups, and write to the /var/log/ and /var/secure/ directories.

The Script

Here’s a breakdown of the create_users.sh script:

Log and Password Files:

The script uses /var/log/user_management.log for logging actions and /var/secure/user_passwords.csv to securely store generated passwords. The /var/secure/ directory is set with restrictive permissions to ensure password security.

Input Validation:

The script checks if an input file is provided and exits with usage instructions if not.

Logging Function:

A simple function logs messages with timestamps to the log file.

Password Generation:

A function generates random 12-character passwords using /dev/urandom.

Processing the Input File:

The script reads each line of the input file, extracts the username and groups, and processes them:

• User Existence Check: If the user already exists, it logs the information and skips to the next line.
• User Creation: It creates the user with the specified personal group and a home directory.
• Additional Groups: If additional groups are specified, the script creates them if they don’t exist and adds the user to these groups.
• Password Setting: It generates and sets a random password for the user and logs this action.

Running the Script

To run the script, I have saved it as create_users.sh, and I have provided the input file as an argument:

chmod +x create_users.sh
sudo ./create_users.sh employee_file

Input File

Here’s the input file (employee_file) looks like:

Kahuna; Backend,DevOps,HR
Dami; DevOps,HR
Sola; Backend

Conclusion

This script automates the process of creating and managing users and groups, ensuring consistency and security. I am currently on a DevOps journey with HNG Internship. To learn more, check HNG Internship and HNG Premium.