pwconv, pwunconv, grpconv, grpunconv - convert to and from shadow passwords and
command creates shadow
optionally existing shadow
command creates passwd
and then removes shadow
command creates gshadow
optionally existing gshadow
command creates group
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
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.
will use the values of PASS_MIN_DAYS
from /etc/login.defs when adding new entries to
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
Display help message and exit.
, --root CHROOT_DIR
Apply changes in the CHROOT_DIR
directory and use the configuration files from the CHROOT_DIR
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
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
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
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).
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
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.
Shadow password suite configuration.