grpconv
, grpunconv convert to and from shadow passwords and groups
see also :
pwunconv - grpunconv - grpck - pwck
Synopsis
pwconv
[options]
pwunconv
[options]
grpconv
[options]
grpunconv
[options]
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examples
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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.
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.
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.
see also
grpck ,
login.defs, pwck .