NAME | SYNOPSIS | DESCRIPTION | OPTIONS | BUGS | CONFIGURATION | FILES | SEE ALSO | COLOPHON

PWCONV(8)                System Management Commands                PWCONV(8)

NAME         top

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

SYNOPSIS         top

       pwconv [options]

       pwunconv [options]

       grpconv [options]

       grpunconv [options]

DESCRIPTION         top

       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         top

       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         top

       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         top

       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         top

       /etc/login.defs
           Shadow password suite configuration.

SEE ALSO         top

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

COLOPHON         top

       This page is part of the shadow-utils (utilities for managing
       accounts and shadow password files) project.  Information about the
       project can be found at ⟨http://pkg-shadow.alioth.debian.org/⟩.  If
       you have a bug report for this manual page, see 
       ⟨http://pkg-shadow.alioth.debian.org/getinvolved.php⟩.  This page was
       obtained from the project's upstream Git repository 
       ⟨git://anonscm.debian.org/git/pkg-shadow/shadow.git⟩ on 2016-10-04.
       If you discover any rendering problems in this HTML version of the
       page, or you believe there is a better or more up-to-date source for
       the page, or you have corrections or improvements to the information
       in this COLOPHON (which is not part of the original manual page),
       send a mail to man-pages@man7.org

shadow-utils 4.3                 10/04/2016                        PWCONV(8)