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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | BUGS | CONFIGURATION | FILES | SEE ALSO | COLOPHON |
PWCONV(8) System Management Commands PWCONV(8)
pwconv, pwunconv, grpconv, grpunconv - convert to and from shadow
passwords and groups
pwconv [options]
pwunconv [options]
grpconv [options]
grpunconv [options]
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.
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.
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.
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.
/etc/login.defs
Shadow password suite configuration.
grpck(8), login.defs(5), pwck(8).
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 2017-07-05.
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 4.4 07/05/2017 PWCONV(8)
Pages that refer to this page: gshadow(5), passwd(5), passwd(5@@shadow-utils), shadow(5)