How to run a specific program as root without a password prompt?

Question

I need to run something as sudo without a password, so I used visudo and added this to my sudoers file:

MYUSERNAME ALL = NOPASSWD: /path/to/my/program

Then I tried it out:

$ sudo /path/to/my/program
[sudo] password for MYUSERNAME: 

Why does it ask for a password? How can I run/use commands as root with a non-root user, without asking for a password?

Answer 1

You have another entry in the sudoers file which also matches your user. The NOPASSWD rule needs to be after that one in order for it to take precedence.

Having done that, sudo will prompt for a password normally for all commands except /path/to/my/program, which it will always let you run without asking for your password.

Answer 2

If there are multiple matching entries in /etc/sudoers, sudo uses the last one. Therefore, if you can execute any command with a password prompt, and you want to be able to execute a particular command without a password prompt, you need the exception last.

myusername ALL = (ALL) ALL
myusername ALL = (root) NOPASSWD: /path/to/my/program

Note the use of (root), to allow the program to be run as root but not as other users. (Don't give more permissions than the minimum required unless you've thought out the implications.)

Note for readers who aren't running Ubuntu or who have changed the default sudo configuration (Ubuntu's sudo is ok by default): Running shell scripts with elevated privileges is risky, you need to start from a clean environment (once the shell has started, it's too late (see Allow setuid on shell scripts), so you need sudo to take care of that). Make sure that you have Defaults env_reset in /etc/sudoers or that this option is the compile-time default (sudo sudo -V | grep env should include Reset the environment to a default set of variables).

Answer 3

I think your syntax is wrong. At least I use the following which works for me:

myusername ALL=(ALL) NOPASSWD: /path/to/executable

Answer 4

When you execute your script you need to run it as sudo /path/to/my/script.

Edit: Based on your comment to another answer, you want to run this from an icon. You will need to create a .desktop file that executes your program with sudo, just like on the terminal.

You could also consider using gtk-sudo for a visual password prompt.

You should probably consider the idea that you shouldn't be running things as root and that changing the system farther down the road so that you don't need root permissions at all would be a better way to go.