Step 1. Open a terminal window, CTRL+ALT+T on my system (Debian KDE after setting up as hotkey)
Step 2. Entered root using command su root
Step 3. Input root password
Step 4. Input command apt-get install sudo -y to install sudo
Step 5. Add user to sudoers file by inputting adduser username sudo, put your username in place of username
Step 6. Set the correct permissions for sudoers file by inputting chmod 0440 /etc/sudoers
Step 7. Type exit and hit Enter until you close your terminal window. Shutdown your system completely and reboot.
Step 8. Open another terminal window.
Step 9. Try any sudo command to check if your username is correctly added to sudoers file. I used sudo echo "Hello World!". If your username has been correctly added to the sudoers list then you will get Hello World! as the terminal response!
