Q:

I added my username to /etc/sudoers but using sudo still asks for password

I entered my username in the sudoers file, but when using sudo in scritps, it still asks for the password. 
This is my sudoers file:  
~: ls -al /etc/sudoers
-r--r-----  1 root  wheel  1297 Aug 14 11:44 /etc/sudoers  

Contents:  
...
%admin  ALL=(ALL) ALL
petruza ALL=(ALL) ALL

(http://pastebin.com/raw.php?i=F38RxeYP)
(I also tried with %petruza but didn't work either)
I have a script to start XAMPP, but it asks for the password anyway:
sudo /Applications/XAMPP/xamppfiles/xampp start

A:

Please realize that disabling the password prompt for sudo is a huge security concern.  
However, it is possible.  Instead of what you already have, add this to your /etc/sudoers file:
petruza ALL=(ALL) NOPASSWD: ALL
Here is some more reading on this topic.