This page gives basic information about Sudo users.

The file used by sudo is /etc/sudoers

Never use vi to open this file. Use the command “visudo”

user1 ALL=/usr/sbin/useradd

By adding this in sido file user1 will be able to add users
ALL means user1 can run this command from any IP. Instead we could specify an IP.

If user1 wants to add a user he should execute the command:
[Hostname]# sudo =/usr/sbin/useradd user2
Password for user1 will be asked

user1 ALL=/usr/sbin/

By this all command =/usr/sbin/ will be accessible to user1

%group1 ALL=/usr/sbin/

By this everyone in the group group1 could run command in /usr/sbin/