The configure file is /etc/sudoers.
For all the group of admin:
%admin ALL=(ALL) NOPASSWD: NOPASSWD ALL
For the user of liuxd:
liuxd ALL=(ALL) NOPASSWD: ALL
For the user of liuxd and just several commands:
liuxd ALL = NOPASSWD: /usr/bin/abc.sh, /usr/sbin/adduser