RHEL7 add user with sudo permission

1, add ordinary users
[[email protected] ~]# Useradd Book//Add a user named book
[[email protected] ~]# passwd book//Change Password
Changing password for the user book.
New UNIX Password://Enter your password here
Retype new UNIX Password://Enter password again
Passwd:all Authentication Tokens updated successfully

2. Then modify the user so that it belongs to the root group, the command is as follows:
[Email protected] ~]# usermod-g root Book

3, add normal users to the sudo group, and password-free login:
Add Write permission to the sudoers file: Use the command "chmod u+w/etc/sudoers"
After executing the visudo command, press "I" to enter edit mode, find "root all= (All) All", add later:
"Book all= (All) Nopasswd:all", then click "ESC" key to quit editing, enter "Wq" (write quit), exit sudoers.
Enter "chmod u-w/etc/sudoers" To remove the Write property of the file
When you switch back to your users with "exit" and then use the sudo whoami command, if you return root, you can use the

RHEL7 add user with sudo permission