Linux Set the password complexity limit, how to set __linux

In Linux, there are several 1 ways to set the password complexity
. One is in the/etc/login.defs file, inside several options
pass_max_days  #密码最长过期天数
pass_min_ Days  #密码最小过期天数
pass_min_len  #密码最小长度
pass_warn_age   7   #密码过期警告天数

2. Another method is to modify the/etc/pam.d/system-auth file to
find password requisite pam_cracklib.so such a line replaced by the following:
password  Requisite pam_cracklib.so retry=5 difok=3 minlen=10 ucredit=-1 lcredit=-3 dcredit=-3 dictpath=/usr/share/  Cracklib/pw_dict

parameter meaning:
5    
least different characters: 3       
Minimum password length: min          
 Capital Letter: 1       
Minimum lowercase letters: 3        
min: 3        
Password Dictionary:/usr/share/cracklib/pw_dict

This setting, you can do a test, but you need to exit root, because the root user is not subject to these restrictions, it can set any password.