如果修改的是root的密碼則即使有錯誤提示也可以修改成功的，但是對於一般的用戶則不會成功，解決方法如下：
Resolve and Remove “BAD PASSWORD: it is based on a dictionary word “in Linux
If you know what you’re doing and want to use weak password in Linux (CentOS, RedHat … etc), follow the steps below.
1. vi /etc/pam.d/system-auth as root.
2. Look for the following two lines:
password requisite pam_cracklib.so try_first_pass retry=3 password sufficient pam_unix.so md5 shadow nullok try_first_pass use_authtok
-
password requisite pam_cracklib.so try_first_pass retry=3 -
password sufficient pam_unix.so md5 shadow nullok try_first_pass use_authtok
3. Comment out the first of the two lines: 註釋掉此行
#password requisite pam_cracklib.so try_first_pass retry=3
4. Remove use_authtok on the second line. Otherwise you’ll get “passwd: Authentication information cannot be recovered” error.
刪除掉 "use_authtok “從第二行，否則你會得到"passwd : Authentication information canot be recovered "的錯誤提示password sufficient pam_unix.so md5 shadow nullok try_first_pass
5. That’s it. Try changing your password again.
搞定，再次嘗試修改密碼（）