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pwunconv(8)


NAME

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

SYNOPSIS

   pwconv [options]

   pwunconv [options]

   grpconv [options]

   grpunconv [options]

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.

OPTIONS

   The options which apply to the pwconv, pwunconv, grpconv, and grpunconv
   commands are:

   -h, --help
       Display help message and exit.

   -R, --root CHROOT_DIR
       Apply changes in the CHROOT_DIR directory and use the configuration
       files from the CHROOT_DIR directory.

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).



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