new-user-creation.md

User Creation Script

The script creates a new user with the specified username, disables the password, and sets up SSH access for the user. It is designed to be run in a terminal on a Linux system with sudo privileges.

Prerequisites

• A Linux system with sudo privileges.
• Bash shell.

Usage

To use the script, follow these steps:

1. Open a terminal.

2. Copy the script into a file, for example, create_user.sh.

   #!/bin/bash
   
   # Check if a username was provided as an argument
   if [ -z "$1" ]; then
     echo "Usage: $0 <username>"
     exit 1
   fi
   
   # Assign the first argument to the USERNAME variable
   USERNAME=$1
   
   # Create the new user
   sudo adduser --disabled-password --gecos "" "$USERNAME"
   
   # Remove the password
   sudo passwd -d "$USERNAME"
   
   # Set password expiry and other properties
   sudo chage -I -1 -m 0 -M 99999 -E -1 "$USERNAME"
   
   # Switch to the new user to set up SSH
   sudo su - "$USERNAME" -c "
   mkdir -p ~/.ssh
   chmod 700 ~/.ssh
   touch ~/.ssh/authorized_keys
   chmod 600 ~/.ssh/authorized_keys
   "
   
   echo "User '$USERNAME' has been created and configured."

3. Make the script executable:

   chmod +x create_user.sh

4. Run the script with the desired username:

   ./create_user.sh <username>

   Replace <username> with the desired username for the new user.

Script Functionality

• Checks for Username: The script checks if a username is provided as an argument. If not, it displays usage instructions and exits.
• Creates User: It creates a new user with the specified username, disabling the password and setting the user information to empty.
• Removes Password: The password for the new user is removed, allowing for passwordless login.
• Sets Password Expiry: Configures the password expiry settings for the user.
• Sets Up SSH Access: Creates the .ssh directory and authorized_keys file for the new user, setting appropriate permissions.

Important Notes

• Ensure that you have the necessary permissions to run the script with sudo.
• The script does not set a password for the new user, which may not be suitable for all environments. Consider security implications before using passwordless accounts.
• You may need to manually add SSH keys to the ~/.ssh/authorized_keys file for the new user to enable SSH access.