linux users to achieve root user password empty

A, sshd default blank password is not allowed
to set PermitEmptyPasswords yes # allow blank password
systemctl restart sshd
Second, delete the user password
passwd -d root
Third, check the user (root) password if space is
passwd -S root
or the system all empty user password:
awk -F ':' '{IF ($ 2 == "") $ 0} Print' / etc / Shadow

# The result is displayed as Empty password,