Linux. To delete expiration interval of user password

Linux. To delete expiration interval of user password
1. login as root
        ls -lh /etc |grep shadow
       
2. change permition
        chmod 600 /etc/shadow
3. edit shadow
        vi /etc/shadow
                change the string
                        oracle:$1$/lFSo3aP$LHkIxXXxkGtveA8cAjk7//:15197:1:90:7:::
                to
                        oracle:$1$/lFSo3aP$LHkIxXXxkGtveA8cAjk7//:15197:1::7:::
4. change permission back
        chmod 400 /etc/shadow