Efficient User and Group Management on Linux: A Bash Script Tutorial

Table Of Content

1. Introduction
2. script overview
3. Conclusion

Introduction

A Bash script is a text file containing a series of commands written in the Bash (Bourne Again SHell) scripting language, which is a command processor that typically runs in a text window where the user types commands to perform actions. A Bash script allows users to automate repetitive tasks, manage system operations, and perform complex operations by executing commands.

As a SysOps engineer, managing user accounts and groups is crucial for maintaining a secure and organized development environment. In this article, I will guide you through a bash script designed to automate user creation, assign groups, set up home directories, and handle permissions efficiently.

The script, create_users.sh, performs the following tasks:

1. Reading Input: It reads a text file containing usernames and their associated groups.

2. User and Group Creation: It creates users and their groups if they do not already exist.

3. Home Directory Setup: It sets up home directories with appropriate permissions and ownership.

4. Password Generation: It generates random passwords for the users.

5. Logging: It logs all actions to /var/log/user_management.log and stores the passwords securely in /var/secure/user_passwords.csv.

Script Overview

Here’s a detailed breakdown of the script:

1. Checking Input Argument: The script checks if the input file is provided as an argument.

if [ -z "$1" ]; then
    echo "Usage: $0 <name-of-text-file>"
    exit 1
fi

1. Initialization: It initializes log and password files and ensures the secure directory exists.

# Function to generate a random password
generate_password() {




    # using 'openssl rand -base64 12’ to generate a 12-character password
    openssl rand -base64 12
}

# Read input file line by line
while IFS=';' read -r username groups; do
    # Create groups if they don't exist
    for group in $(echo "$groups" | tr ',' ' '); do
      groupadd "$group" 2>/dev/null || echo "Group $group already exists"
    done

create user

useradd -m "$username" -G "$groups" 2>/dev/null || echo "User $username already exists"

1. command that sets passwords

password=$(generate_password)
echo "$username:$password" | chpasswd

1. Command that logs actions

echo "$(date '+%Y-%m-%d %H:%M:%S') - Created user $username with groups: $groups" >> "$log_file"

1. Command that stores password securely

echo "$username:$password" >> "$password_file"
done < "$input_file"

Conclusion

This script simplifies managing users and groups on a Linux system, ensuring security and efficiency. Automating these tasks not only saves time but also reduces the risk of human error.

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You can also find the code to the bash script on my GitHub here Linsmed