PWCONV(8)                                          System Management Commands                                          PWCONV(8)



NAME
       pwconv, pwunconv, grpconv, grpunconv - convert to and from shadow passwords and groups

SYNOPSIS
       pwconv

       pwunconv

       grpconv

       grpunconv

DESCRIPTION
       The pwconv command creates shadow from passwd and an optionally existing shadow.

       The pwunconv command creates passwd from passwd and shadow and then removes shadow.

       The grpconv command creates gshadow from group and an optionally existing gshadow.

       The grpunconv command creates group from group and gshadow and then removes gshadow.

       These four programs all operate on the normal and shadow password and group files: /etc/passwd, /etc/group, /etc/shadow,
       and /etc/gshadow.

       Each program acquires the necessary locks before conversion.  pwconv and grpconv are similar. First, entries in the
       shadowed file which don't exist in the main file are removed. Then, shadowed entries which don't have `x' as the password
       in the main file are updated. Any missing shadowed entries are added. Finally, passwords in the main file are replaced
       with `x'. These programs can be used for initial conversion as well to update the shadowed file if the main file is
       edited by hand.

       pwconv will use the values of PASS_MIN_DAYS, PASS_MAX_DAYS, and PASS_WARN_AGE from /etc/login.defs when adding new
       entries to /etc/shadow.

       Likewise pwunconv and grpunconv are similar. Passwords in the main file are updated from the shadowed file. Entries which
       exist in the main file but not in the shadowed file are left alone. Finally, the shadowed file is removed. Some password
       aging information is lost by pwunconv. It will convert what it can.

BUGS
       Errors in the password or group files (such as invalid or duplicate entries) may cause these programs to loop forever or
       fail in other strange ways. Please run pwck and grpck to correct any such errors before converting to or from shadow
       passwords or groups.

CONFIGURATION
       The following configuration variable in /etc/login.defs changes the behavior of grpconv and grpunconv:

       MAX_MEMBERS_PER_GROUP (number)
           Maximum members per group entry. When the maximum is reached, a new group entry (line) is started in /etc/group (with
           the same name, same password, and same GID).

           The default value is 0, meaning that there are no limits in the number of members in a group.

           This feature (split group) permits to limit the length of lines in the group file. This is useful to make sure that
           lines for NIS groups are not larger than 1024 characters.

           If you need to enforce such limit, you can use 25.

           Note: split groups may not be supported by all tools (even in the Shadow toolsuite). You should not use this variable
           unless you really need it.

       The following configuration variables in /etc/login.defs change the behavior of pwconv:

       PASS_MAX_DAYS (number)
           The maximum number of days a password may be used. If the password is older than this, a password change will be
           forced. If not specified, -1 will be assumed (which disables the restriction).

       PASS_MIN_DAYS (number)
           The minimum number of days allowed between password changes. Any password changes attempted sooner than this will be
           rejected. If not specified, -1 will be assumed (which disables the restriction).

       PASS_WARN_AGE (number)
           The number of days warning given before a password expires. A zero means warning is given only upon the day of
           expiration, a negative value means no warning is given. If not specified, no warning will be provided.

FILES
       /etc/login.defs
           Shadow password suite configuration.

SEE ALSO
       grpck(8), login.defs(5), pwck(8).



System Management Commands                                 07/24/2009                                                  PWCONV(8)