The /etc/shadow file  contains the encrypted password information for 
user's accounts and optional password aging information. 

Included are:

           1 Login name

           2 Encrypted password

           3 Days since Jan 1, 1970 that password was last changed

           4 Days before password may be changed

           5 Days after which password must be changed

           6 Days before password is to expire that user is warned

           7 Days after password expires that account is disabled

           8 Days since Jan 1, 1970 that account is disabled

           9 A reserved field