Poweroff or Reboot as normal User

I changed /etc/sudoers so that every user that is in the admin group can execute the following commands without being ask for a password.

sudo halt
sudo reboot
sudo poweroff

You just need to add the following lines to /etc/sudoers

## Admin user group is allowed to execute halt and reboot 
%admin ALL=NOPASSWD: /sbin/halt, /sbin/reboot, /sbin/poweroff

and add yourself to the admin group.

If you want only one user to be able to do this just remove the %admin and replace it with username like this

## user is allowed to execute halt and reboot 
stormvirux ALL=NOPASSWD: /sbin/halt, /sbin/reboot, /sbin/poweroff

You can find out more about /etc/sudoers with man sudoers or the online manpage

You can also create a new file under /etc/sudoers.d name it as you wish(I named it 'shutdown'), and put the following lines inside:

# Allows me to shutdown the system without a password

yourUserName ALL = NOPASSWD: /sbin/halt, /sbin/reboot, /sbin/poweroff

Just change "yourUserName" for YOUR User Name, and add or remove commands to use, personally I use it only for shutdown. One of the main difference of creating a particular file under sudoers.d is that this file will survive System Upgrades

You can also achieve this by trick with setuid. I don't know if it will work on all systems, because they sometimes ignore setuid/setgid bit.

You can specify a group of users who can perform change of system state in my case it was adm. Then add appropriate users to this group.

gpasswd -a $USER adm

Specify permissions:

chmod 4550 /usr/bin/reboot

ls -l outpus should look like this:

-r-sr-x--- 1 root adm 18928 Mar 13  2015 /usr/bin/reboot

Afterwards you can just type:

reboot