How to add sudo user in linux?

■ Requirement : add sudo user
■ OS Environment : Linux[RHEL, Centos]
■ Application:sudo
■ Implementation Steps : 

1. Add user : 

$ useradd test123

2. add user to wheel group

$ usermod -G wheel -a test123 

3. Uncomment following in /etc/sudoers file :

# Uncomment to allow people in group wheel to run all commands
%wheel ALL=(ALL) ALL

4. [Optional]Add user test123 in /etc/sudoers file :

# User privilege specification

root ALL=(ALL) ALL
test123 ALL=(ALL) ALL

NOTE : test123 has full access as root has. It can be enabled particular commands to be executed by test123. Check manual of sudo in more detail.