How can I create an administrator user from the command line?

Add the user to the sudo group with:

adduser <username> sudo

(If you're running Ubuntu 11.10 or earlier, use the admin group.)

Default values are stored in /etc/adduser.conf, you can check them with

less /etc/adduser.conf

To create a user and add it directly to the sudo group use

adduser <username> --group sudo

(Again, use admin in place of sudo for 11.10 and earlier.)

Have a look at all the options you have with adduser here.

To create a new user with admin privileges in Ubuntu 12.04 and later:

adduser <username> --group sudo

In Ubuntu 11.10 and earlier, use this instead:

adduser <username> --group admin

To modify a existing user (12.04 and later):

adduser <username> --group sudo

or

sudo usermod -aG sudo <username>

(Or for 11.10 and earlier: sudo usermod -aG admin <username>)

-a stands for append whereas -G stands for groups. With the -a and -G flags as shown above, the sudo (or admin) group will be added to the list of groups of which the user is a member.

The other answers are correct but you also asked about the home directory. You will also need a password for the new user.

sudo useradd *new-admin-username* -s /bin/bash -g sudo -m

• -s sets the user's login shell
• -m makes the user's home directory if it doesn't exist: /home/*new-admin-username*
• -g adds the user to the sudo group so they will have admin privileges (>11.10)

Once created, add a password for the user:

sudo passwd *new-admin-username*

Login to the user to see if everything worked:

su *new-admin-username*
cd ~/
pwd