Series 4: Ep 6: Bash Scripting Essentials

Master automation in Linux with Bash scripts! Discover how to create and debug scripts for user setup, including creating new users, setting passwords, adding them to groups, configuring SSH key-based login, and setting password expiry. We’ll also cover testing and verification. Script: #!/bin/bash #Variables USERNAME="Jason" # User account name PASSWORD="P@ssw0rd" # User password GROUP="developers" # Custom group name SSH_DIR="/home/$USERNAME/.ssh" PUB_KEY="ssh-rsa AAAAB3...your-public-key... user@kali" # Replace with your actual public key #Step 1: Check if user already exists if id "$USERNAME" &>/dev/null; then echo "Error: User '$USERNAME' already exists!" exit 1 fi #Step 2: Create user and set password echo "Creating user '$USERNAME'..." useradd -m -s /bin/bash "$USERNAME" if [ $? -ne 0 ]; then echo "Error: Failed to create user '$USERNAME'" exit 1 fi echo "$USERNAME:$PASSWORD" | chpasswd echo "Password set for user '$USERNAME'." #Step 3: Add user to sudoers echo "Granting sudo access to '$USERNAME'..." usermod -aG sudo "$USERNAME" if [ $? -ne 0 ]; then echo "Error: Failed to add '$USERNAME' to sudoers" exit 1 fi #Step 4: Create custom group and add user echo "Creating group '$GROUP' and adding user..." groupadd "$GROUP" 2>/dev/null usermod -aG "$GROUP" "$USERNAME" if [ $? -ne 0 ]; then echo "Error: Failed to add '$USERNAME' to group '$GROUP'" exit 1 fi #Step 5: Setup SSH key-based authentication echo "Setting up SSH key-based authentication..." mkdir -p "$SSH_DIR" echo "$PUB_KEY" > "$SSH_DIR/authorized_keys" chmod 600 "$SSH_DIR/authorized_keys" chmod 700 "$SSH_DIR" chown -R "$USERNAME:$USERNAME" "$SSH_DIR" if [ $? -ne 0 ]; then echo "Error: Failed to set up SSH keys" exit 1 fi echo "SSH keys configured for '$USERNAME'." #Step 6: Set password expiry to 30 days echo "Setting password expiry policy for '$USERNAME'..." chage -M 30 "$USERNAME" if [ $? -ne 0 ]; then echo "Error: Failed to set password expiry" exit 1 fi #Step 7: Log activity to /var/log/user_setup.log LOG_FILE="/var/log/user_setup.log" echo "$(date) - User '$USERNAME' created and configured" >> "$LOG_FILE" if [ $? -ne 0 ]; then echo "Error: Failed to write log to $LOG_FILE" exit 1 fi #Step 8: Confirmation Message echo "User '$USERNAME' created and configured successfully!"