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Manual for shadow - man 5 shadow

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SHADOW(5)                                                            SHADOW(5)

       shadow(3,5) - encrypted password file(1,n)

       shadow(3,5)  contains the encrypted password information for user's accounts
       and optional the password aging information. Included is:

         login(1,3,5) name

         encrypted password

         days since Jan 1, 1970 that password was last changed

         days before password may be changed

         days after which password must be changed

         days before password is to expire that user is warned

         days after password expires that account is disabled

         days since Jan 1, 1970 that account is disabled

         a reserved field

       The password field must be filled. The encrypted password  consists  of
       13 to 24 characters from the 64 characters alphabet a thru z, A thru Z,
       0 thru 9, \. and /. Optionally it can start with a "$" character.  This
       means  the  encrypted  password  was  generated using another (not DES)
       algorithm. For example if(3,n) it starts with "$1$" it means  the  MD5-based
       algorithm was used.

       Refer to crypt(3) for details on how this string(3,n) is interpreted.

       The  date  of  the  last password change is given as the number of days
       since Jan 1, 1970. The password may not  be  changed  again  until  the
       proper  number of days have passed, and must be changed after the maxi-
       mum number of days. If the minimum number of days required  is  greater
       than  the  maximum  number  of  day  allowed,  this password may not be
       changed by the user.

       An account is considered to be inactive and is disabled if(3,n) the password
       is  not  changed within the specified number of days after the password
       expires. An account will also be disabled on the specified day  regard-
       less(1,3) of other password expiration information.

       This  information  supersedes  any password or password age information
       present in(1,8) /etc/passwd(1,5).

       This file(1,n) must not be readable by regular users(1,5) if(3,n) password security is
       to be maintained.

              user account information

              secure user account information

       chage(1),  login(1,3,5)(1),  passwd(1,5)(1),  su(1),  passwd(1,5)(5),  pwconv(8),  pwun-
       conv(8), sulogin(8)

       Julianne Frances Haugh (


References for this manual (incoming links)