~ $ su
Password:
configuration error - unknown item 'PASS_MIN_LEN' (notify administrator)

 ~ # grep -ril 'PASS_MIN_LEN' /etc/*
/etc/login.defs

~ # vi /etc/login.defs
#
# /etc/login.defs - Configuration control definitions for the login package.
#
#       $Id: login.defs,v 1.6 2006/03/12 23:47:08 flameeyes Exp $
#
# Three items must be defined:  MAIL_DIR, ENV_SUPATH, and ENV_PATH.
# If unspecified, some arbitrary (and possibly incorrect) value will
# be assumed.  All other items are optional - if not specified then
# the described action or option will be inhibited.
#
# Comment lines (lines beginning with "#") and blank lines are ignored.
#
# Modified for Linux.  --marekm

#
# Delay in seconds before being allowed another attempt after a login failure
#
FAIL_DELAY              3

#
# Enable display of unknown usernames when login failures are recorded.
#
LOG_UNKFAIL_ENAB        no

#
# Enable logging of successful logins
#
LOG_OK_LOGINS           no

#
# Enable "syslog" logging of su activity - in addition to sulog file logging.
# SYSLOG_SG_ENAB does the same for newgrp and sg.
#
SYSLOG_SU_ENAB          yes
SYSLOG_SG_ENAB          yes

#
# If defined, either full pathname of a file containing device names or
# a ":" delimited list of device names.  Root logins will be allowed only
# upon these devices.
#
CONSOLE         /etc/securetty
#CONSOLE        console:tty01:tty02:tty03:tty04

#
# If defined, all su activity is logged to this file.
#
#SULOG_FILE     /var/log/sulog

#
# If defined, file which maps tty line to TERM environment parameter.
# Each line of the file is in a format something like "vt100  tty01".
#
#TTYTYPE_FILE   /etc/ttytype

#
# If defined, the command name to display when running "su -".  For
# example, if this is defined as "su" then a "ps" will display the
# command is "-su".  If not defined, then "ps" would display the
# name of the shell actually being run, e.g. something like "-sh".
#
SU_NAME         su

#
# *REQUIRED*
#   Directory where mailboxes reside, _or_ name of file, relative to the
#   home directory.  If you _do_ define both, MAIL_DIR takes precedence.
#
MAIL_DIR /var/spool/mail

#
# If defined, file which inhibits all the usual chatter during the login
# sequence.  If a full pathname, then hushed mode will be enabled if the
# user's name or shell are found in the file.  If not a full pathname, then
# hushed mode will be enabled if the file exists in the user's home directory.
#
HUSHLOGIN_FILE  .hushlogin
#HUSHLOGIN_FILE /etc/hushlogins

#
# *REQUIRED*  The default PATH settings, for superuser and normal users.
#
# (they are minimal, add the rest in the shell startup files)
ENV_SUPATH      PATH=/sbin:/bin:/usr/sbin:/usr/bin
ENV_PATH        PATH=/bin:/usr/bin

#
# Terminal permissions
#
#       TTYGROUP        Login tty will be assigned this group ownership.
#       TTYPERM         Login tty will be set to this permission.
#
# If you have a "write" program which is "setgid" to a special group
# which owns the terminals, define TTYGROUP to the group number and
# TTYPERM to 0620.  Otherwise leave TTYGROUP commented out and assign
# TTYPERM to either 622 or 600.
#
TTYGROUP        tty
TTYPERM         0600

#
# Login configuration initializations:
#
#       ERASECHAR       Terminal ERASE character ('\010' = backspace).
#       KILLCHAR        Terminal KILL character ('\025' = CTRL/U).
#       UMASK           Default "umask" value.
#
# The ERASECHAR and KILLCHAR are used only on System V machines.
# The ULIMIT is used only if the system supports it.
# (now it works with setrlimit too; ulimit is in 512-byte units)
#
# Prefix these values with "0" to get octal, "0x" to get hexadecimal.
#
ERASECHAR       0177
KILLCHAR        025
UMASK           022

#
# Password aging controls:
#
#       PASS_MAX_DAYS   Maximum number of days a password may be used.
#       PASS_MIN_DAYS   Minimum number of days allowed between password changes.
#       PASS_WARN_AGE   Number of days warning given before a password expires.
#
PASS_MAX_DAYS 99999
PASS_MIN_DAYS 0
PASS_WARN_AGE 7

#
# Min/max values for automatic uid selection in useradd
#
UID_MIN 1000
UID_MAX 60000

#
# Min/max values for automatic gid selection in groupadd
#
GID_MIN 100
GID_MAX 60000

#
# Max number of login retries if password is bad
#
LOGIN_RETRIES           3

#
# Max time in seconds for login
#
LOGIN_TIMEOUT           60

#
# Which fields may be changed by regular users using chfn - use
# any combination of letters "frwh" (full name, room number, work
# phone, home phone).  If not defined, no changes are allowed.
# For backward compatibility, "yes" = "rwh" and "no" = "frwh".
#
CHFN_RESTRICT           rwh

#
# List of groups to add to the user's supplementary group set
# when logging in on the console (as determined by the CONSOLE
# setting).  Default is none.
#
# Use with caution - it is possible for users to gain permanent
# access to these groups, even when not logged in on the console.
# How to do it is left as an exercise for the reader...
#
#CONSOLE_GROUPS         floppy:audio:cdrom

#
# Should login be allowed if we can't cd to the home directory?
# Default in no.
#
DEFAULT_HOME    yes

#
# If defined, this command is run when removing a user.
# It should remove any at/cron/print jobs etc. owned by
# the user to be removed (passed as the first argument).
#
#USERDEL_CMD    /usr/sbin/userdel_local

#
# When prompting for password without echo, getpass() can optionally
# display a random number (in the range 1 to GETPASS_ASTERISKS) of '*'
# characters for each character typed.  This feature is designed to
# confuse people looking over your shoulder when you enter a password :-).
# Also, the new getpass() accepts both Backspace (8) and Delete (127)
# keys to delete previous character (to cope with different terminal
# types), Control-U to delete all characters, and beeps when there are
# no more characters to delete, or too many characters entered.
#
# Setting GETPASS_ASTERISKS to 1 results in more traditional behaviour -
# exactly one '*' displayed for each character typed.
#
# Setting GETPASS_ASTERISKS to 0 disables the '*' characters (Backspace,
# Delete, Control-U and beep continue to work as described above).
#
# Setting GETPASS_ASTERISKS to -1 reverts to the traditional getpass()
# without any new features.  This is the default.
#
GETPASS_ASTERISKS 0

#
# Enable setting of the umask group bits to be the same as owner bits
# (examples: 022 -> 002, 077 -> 007) for non-root users, if the uid is
# the same as gid, and username is the same as the primary group name.
#
# This also enables userdel to remove user groups if no members exist.
#
USERGROUPS_ENAB yes

PASS_MIN_LEN 5