pwconv

PWCONV(8)                  System Management Commands                  PWCONV(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).



shadow-utils 4.8.1                 01/23/2020                          PWCONV(8)