Adding a user to the Sudoers list in Ubuntu 14.04

Try to re-install the package sudo. If this don’t work try enter these in the file manually <br><pre># <br># This file MUST be edited with the ‘visudo’ command as root. <br># <br># Please consider adding local content in /etc/sudoers.d/ instead of <br># directly modifying this file. <br># <br># See the man page for details on how to write a sudoers file. <br># <br>Defaults env_reset <br>Defaults mail_badpass <br>Defaults secure_path=“/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin” <br> <br># Host alias specification <br> <br># User alias specification <br> <br># Cmnd alias specification <br> <br># User privilege specification <br>root ALL=(ALL:ALL) ALL <br> <br># Allow members of group sudo to execute any command <br>%sudo ALL=(ALL:ALL) ALL <br> <br># See sudoers(5) for more information on “#include” directives: <br> <br>#includedir /etc/sudoers.d</pre>

If you’re already running as root, check to see if the sudoers file exists by typing in: <br> <br>ls /etc/sudoers <br> <br>That will kick the file listing out if the file exists. If you have the file available, go with: <br> <br># vi /etc/sudoers <br> <br>You should be able to get to ‘insert’ mode by pressing ‘i’ and you will see a notice about it being a read-only file (disregard that since you will be root), enter in the new user, hit escape, and force the file to save by entering in ‘:wq!’ <br> <br>Hope that helps.

As a root perform:

Step 1: adduser demo Step 2: gpasswd -a demo sudo Step 3: passwd demo

Reference: https://www.digitalocean.com/community/tutorials/initial-server-setup-with-ubuntu-14-04