### Introduction As a SysOps engineer, managing users and groups on a server is one of your routine tasks. This process can be quite time-consuming and susceptible to errors, particularly when handling numerous users. Automating these tasks is crucial for achieving efficiency and reliability. This article will guide you through a Bash script that automates the creation of users and groups, sets up home directories with correct permissions, generates random passwords, and logs all actions. ### Bash Bash which stands for "Bourne Again Shell" is a command language interpreter and scripting language commonly used in Unix-like operating systems, such as linux and macOS. It's the default shell for most linux distributions and is widely used for automation tasks, managing system operations, and write scrips. #### What is Bash script? A Bash script is a file typically ending with the extension .sh that contain a logical series of related commands to be executed This project was inspired by HNG internship 11 https://hng.tech/hire, DevOps track of stage one. visit https://hng.tech/internship to learn more about the program ### Prerequisite Before we start, ensure you have: - Access to a linux server with root privileges - Basic knowledge of Bash scripting ### Script Overview The script we'll create will: 1. Create users and groups 2. set up home directories with the correct permissions 3. Generate random passwords for users 4. Log all actions to a specified log file ### User Management Automation project Let's dive into an extensive project that will show us a step by step guide on how to create user and group management with Bash script. Here is a step by step guide on how to create user and groups management: ## Creating the script file First and foremost, Create a new Bash script file ``` touch create_user.sh ``` Open the file in your preferred text editor: ``` vim create_user.sh ``` Create an employee file where users and group would be located ``` touch employeefile.txt ``` edit your user_data.txt file with a text editor and enter the following user and group below: ``` vim employeefile.txt ``` ### Example Input File light; sudo,dev, www-data idimma;sudo mayowa;dev,www-data **Insert the following script below into your 'create_users.sh' file** ### The Script ``` #!/bin/bash # Define log and password files LOG_FILE="/var/log/user_management.log" PASSWORD_FILE="/var/secure/user_passwords.txt" # Create log and password files if they don't exist touch $LOG_FILE mkdir -p /var/secure touch $PASSWORD_FILE # Function to log messages log_message() { echo "$(date +'%Y-%m-%d %H:%M:%S') - $1" | tee -a $LOG_FILE } # Function to generate random password generate_password() { tr -dc A-Za-z0-9 " exit 1 fi # Read the input file INPUT_FILE=$1 # Check if the input file exists if [ ! -f $INPUT_FILE ]; then echo "Input file not found!" exit 1 fi while IFS=';' read -r username groups; do # Remove leading and trailing whitespaces username=$(echo $username | xargs) groups=$(echo $groups | xargs) if id "$username" &>/dev/null; then log_message "User $username already exists. Skipping..." continue fi # Create a personal group for the user groupadd $username if [ $? -ne 0 ]; then log_message "Failed to create group $username." continue fi log_message "Group $username created successfully." # Create user and add to personal group useradd -m -g $username -s /bin/bash $username if [ $? -ne 0 ]; then log_message "Failed to create user $username." continue fi log_message "User $username created successfully." # Create additional groups if they don't exist and add user to groups IFS=',' read -ra group_array <<< "$groups" for group in "${group_array[@]}"; do group=$(echo $group | xargs) if [ -z "$group" ]; then continue fi if ! getent group $group >/dev/null; then groupadd $group if [ $? -ne 0 ]; then log_message "Failed to create group $group." continue fi log_message "Group $group created successfully." fi usermod -aG $group $username log_message "User $username added to group $group." done # Set up home directory permissions chmod 700 /home/$username chown $username:$username /home/$username log_message "Permissions set for home directory of $username." # Generate random password and store it password=$(generate_password) echo "$username:$password" | chpasswd echo "$username:$password" >> $PASSWORD_FILE log_message "Password set for user $username." done < "$INPUT_FILE" log_message "User and group creation process completed." exit 0 ``` **Make the script executable** ``` chmod +x create_user.sh ``` **Execute the script** ``` sudo bash ./create_users.sh employeefile.txt ``` ## Defining the Script Start by defining the script header and setting some initial variables: **Define Log and Password Files** ``` #!/bin/bash # Define log and password files LOG_FILE="/var/log/user_management.log" PASSWORD_FILE="/var/secure/user_passwords.txt" ``` These lines set the paths for the log file and the file where passwords will be stored. **Create Log and Password Files if They Don't Exist** ``` # Create log and password files if they don't exist touch $LOG_FILE mkdir -p /var/secure touch $PASSWORD_FILE ``` - touch $LOG_FILE creates the log file if it doesn't already exist. - mkdir -p /var/secure creates the directory /var/secure if it doesn't exist. - touch $PASSWORD_FILE creates the password file if it doesn't exist. **Function to Log Messages** ``` # Function to log messages log_message() { echo "$(date +'%Y-%m-%d %H:%M:%S') - $1" | tee -a $LOG_FILE } ``` This function logs messages with a timestamp. tee -a $LOG_FILE appends the log message to the log file while also displaying it on the console. **Function to Generate Random Password** ``` # Function to generate random password generate_password() { tr -dc A-Za-z0-9 " exit 1 fi ``` This part ensures that the script is called with exactly one argument (the input file). If not, it displays a usage message and exits. **Read the Input File** ``` # Read the input file INPUT_FILE=$1 ``` This assigns the first argument (input file) to the variable INPUT_FILE. **Check if the Input File Exists** ``` # Check if the input file exists if [ ! -f $INPUT_FILE ]; then echo "Input file not found!" exit 1 fi ``` This checks if the input file exists. If not, it prints an error message and exits. **Process Each Line of the Input File** ``` while IFS=';' read -r username groups; do # Remove leading and trailing whitespaces username=$(echo $username | xargs) groups=$(echo $groups | xargs) ``` - IFS=';' read -r username groups reads each line of the input file, splitting the line into username and groups using ; as a delimiter. - xargs is used to trim leading and trailing whitespaces from username and groups. **Check if the User Already Exists** ``` if id "$username" &>/dev/null; then log_message "User $username already exists. Skipping..." continue fi ``` This checks if the user already exists. If the user exists, it logs a message and skips to the next iteration. **Create a Personal Group for the User** ``` # Create a personal group for the user groupadd $username if [ $? -ne 0 ]; then log_message "Failed to create group $username." continue fi log_message "Group $username created successfully." ``` - groupadd $username creates a new group with the same name as the user. - $? checks the exit status of the groupadd command. If it's not zero (indicating an error), it logs a failure message and skips to the next iteration. - If the group is created successfully, it logs a success message. Create the User and Add to Personal Group ``` # Create user and add to personal group useradd -m -g $username -s /bin/bash $username if [ $? -ne 0 ]; then log_message "Failed to create user $username." continue fi log_message "User $username created successfully." ``` - useradd -m -g $username -s /bin/bash $username creates the user with a home directory and assigns the personal group. - The exit status is checked, and appropriate messages are logged. **Create Additional Groups and Add User to Them** ``` # Create additional groups if they don't exist and add user to groups IFS=',' read -ra group_array <<< "$groups" for group in "${group_array[@]}"; do group=$(echo $group | xargs) if [ -z "$group" ]; then continue fi if ! getent group $group >/dev/null; then groupadd $group if [ $? -ne 0 ]; then log_message "Failed to create group $group." continue fi log_message "Group $group created successfully." fi usermod -aG $group $username log_message "User $username added to group $group." done ``` - IFS=',' read -ra group_array <<< "$groups" splits the groups string into an array. - The script iterates over the array, trims whitespaces, checks if the group is empty, and continues to the next iteration if it is. - It checks if each group exists using getent group $group. If the group does not exist, it creates it. - The user is added to the group using usermod -aG $group $username. Appropriate messages are logged throughout **Set Up Home Directory Permissions** ``` # Set up home directory permissions chmod 700 /home/$username chown $username:$username /home/$username log_message "Permissions set for home directory of $username." ``` - chmod 700 /home/$username sets the permissions of the user's home directory. - chown $username:$username /home/$username changes the ownership of the home directory to the user. - A log message is recorded. **Generate Random Password and Store It** ``` # Generate random password and store it password=$(generate_password) echo "$username:$password" | chpasswd echo "$username:$password" >> $PASSWORD_FILE log_message "Password set for user $username." ``` - password=$(generate_password) generates a random password. - echo "$username:$password" | chpasswd sets the user's password. - The password is stored in the password file. - A log message is recorded. **Complete the Process** ``` done < "$INPUT_FILE" log_message "User and group creation process completed." exit 0 ``` - The done statement ends the while loop. - A log message indicates that the process is complete. - exit 0 exits the script successfully. This detailed breakdown should help you understand each part of the script and its function as you run it in your terminal.

tim_shantel

Automating user and group management with Bash

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