Provided by:
passwd_4.0.18.1-9_i386 
NAME
pwconv, pwunconv, grpconv, grpunconv - convert to and from shadow
passwords and groups
SYNOPSIS
pwconv
pwunconv
grpconv
grpunconv
DESCRIPTION
pwconv creates shadow from passwd and an optionally existing shadow.
pwunconv creates passwd from passwd and shadow and then removes shadow.
grpconv creates gshadow from group and an optionally existing gshadow.
grpunconv 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.
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.
FILES
/etc/login.defs
Shadow password suite configuration.
grpck(8), login.defs(5), pwck(8).