Linux how to let ordinary users use sudo permissions do not need to enter a password

Linux how to let ordinary users use sudo permissions do not need to enter a password.
See a lot of information on the Internet, all only said in/etc/sudoers add the following line:
Username all= (All) Nopasswd:all

However, when you actually use sudo, you still need to enter the password after Setup, so after your own testing, you also need to create a user group sudo (the name may not necessarily have to use sudo), add username to this group.
# Groupadd sudo
# usermod-g sudo username

Through the practice found that the redhat5.6 above do not need to configure the user group, directly add username all= (All) Nopasswd:all, if you encounter only add the user can not be able to try to add the way Users group.

Linux how to let ordinary users use sudo permissions do not need to enter a password (GO)