Linux shadow file and passwd file problem solution

=====================Problem=========================================
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If passwd and shadow file problem in linux that is not doing edit, delete or write.
If shows "passwd: Authentication token manipulation error"
If  # chmod 755 shadow
chmod: changing permissions of `shadow': Operation not permitted
If
adduser khan
adduser: cannot open shadow password file

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===================== Solutions by Tayab Khan ==============
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# lsattr /etc/passwd
# chattr -i /etc/passwd
# lsattr /etc/shadow
-----a------- /etc/shadow
# chattr -a /etc/shadow
# chattr -i /etc/shadow
# lsattr /etc/shadow
------------- /etc/shadow
# lsattr /etc/passwd
------------- /etc/passwd

Now adduser, change passwords and edit anything is shadow file
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