Add/Delete sudo user

Original https://www.digitalocean.com/community/tutorials/how-to-create-a-sudo-user-on-ubuntu-quickstart

Steps to Create a New Sudo User

1. Log in to your server as the root user.

   
   ssh root@server_ip_address
   
   
   

2. Use the adduser command to add a new user to your system.
   Be sure to replace username with the user that you want to create.

   
   adduser username
   
   
   

   • Set and confirm the new user's password at the prompt. A strong password is highly recommended!

     
     Set password prompts:
     Enter new UNIX password:
     Retype new UNIX password:
     passwd: password updated successfully
     

   • Follow the prompts to set the new user's information. It is fine to accept the defaults to leave all of this information blank.

     
     User information prompts:
     Changing the user information for username
     Enter the new value, or press ENTER for the default
         Full Name []:
         Room Number []:
         Work Phone []:
         Home Phone []:
         Other []:
     Is the information correct? [Y/n]
     

3. Use the usermod command to add the user to the sudo group.

   
   usermod -aG sudo username
   
   
   

   By default, on Ubuntu, members of the sudo group have sudo privileges.
4. Test sudo access on new user account
• Use the su command to switch to the new user account.

  
  su - username
  
  
  

• As the new user, verify that you can use sudo by prepending "sudo" to the command that you want to run with superuser privileges.

  
  sudo command_to_run
  
  
  

• For example, you can list the contents of the /root directory, which is normally only accessible to the root user.

  
  sudo ls -la /root
  
  
  

• The first time you use sudo in a session, you will be prompted for the password of the user account. Enter the password to proceed.

  
  Output:
  [sudo] password for username:
  

  If your user is in the proper group and you entered the password correctly, the command that you issued with sudo should run with root privileges.

How To Delete a User

In the event that you no longer need a user, it is best to delete the old account.

You can delete the user itself, without deleting any of his or her files by typing this as root:

deluser newuser

If you are signed in as another non-root user with sudo privileges, you could instead type:

sudo deluser newuser

If, instead, you want to delete the user's home directory when the user is deleted, you can issue the following command as root:

deluser --remove-home newuser

If you're running this as a non-root user with sudo privileges, you would instead type:

sudo deluser --remove-home newuser

If you had previously configured sudo privileges for the user you deleted, you may want to remove the relevant line again by typing:

visudo

Or use this if you are a non-root user with sudo privileges:

sudo visudo

root    ALL=(ALL:ALL) ALL
newuser ALL=(ALL:ALL) ALL   # DELETE THIS LINE

This will prevent a new user created with the same name from being accidentally given sudo privileges.