Ubuntu – How to run sudo command with no password


How does the ubuntu user on the AWS images for Ubuntu Server 12.04 have passwordless sudo for all commands when there is no configuration for it in /etc/sudoers?

I'm using Ubuntu server 12.04 on Amazon. I want to add a new user that has the same behavior as the default Ubuntu user. Specifically I want passwordless sudo for this new user.

So I've added a new user and went to edit /etc/sudoers (using visudo of course). From reading that file it seemed like the default ubuntu user was getting it's passwordless sudo from being a member of the admin group. So I added my new user to that. Which didn't work. Then I tried adding the NOPASSWD directive to sudoers. Which also didn't work.

Anyway, now I'm just curious. How does the ubuntu user get passwordless privileges if they aren't defined in /etc/sudoers. What is the mechanism that allows this?

Best Answer

Okay, I have discovered the answer so may as well put it here for completeness. At the end of /etc/sudoers there is what I thought was just a comment:

#includedir /etc/sudoers.d

However this actually includes the contents of that directory. Inside of which is the file /etc/sudoers.d/90-cloudimg-ubuntu. Which has the expected contents

# ubuntu user is default user in cloud-images.
# It needs passwordless sudo functionality.

So that is where the sudo configuration for the default ubuntu user lives.

You should edit this file using visudo. The following command will let you edit the correct file with visudo.

sudo visudo -f /etc/sudoers.d/90-cloudimg-ubuntu

And add a line like:


At the end.

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