The
/etc/login.defs
file defines the site-specific configuration for the shadow password suite. This file is required. Absence of this file will not prevent system operation, but will probably result in undesirable operation.
This file is a readable text file, each line of the file describing one configuration parameter. The lines consist of a configuration name and value, separated by whitespace. Blank lines and comment lines are ignored. Comments are introduced with a "#" pound sign and the pound sign must be the first non-white character of the line.
Parameter values may be of four types: strings, booleans, numbers, and long numbers. A string is comprised of any printable characters. A boolean should be either the value "yes" or "no". An undefined boolean parameter or one with a value other than these will be given a "no" value. Numbers (both regular and long) may be either decimal values, octal values (precede the value with "0") or hexadecimal values (precede the value with "0x"). The maximum value of the regular and long numeric parameters is machine-dependent.
The following configuration items are provided:
CHFN_AUTH (boolean)
If
yes, the
chfn
and
chsh
programs will require authentication before making any changes, unless run by the superuser.
CHFN_RESTRICT (string)
This parameter specifies which values in the
gecos
field of the
/etc/passwd
file may be changed by regular users using the
chfn
program. It can be any combination of letters
f
,r,
w,
h, for Full name, Room number, Work phone, and Home phone, respectively. For backward compatibility, "yes" is equivalent to "rwh" and "no" is equivalent to "frwh". If not specified, only the superuser can make any changes. The most restrictive setting is better achieved by not installing
chfn
SUID.
GID_MAX (number), GID_MIN (number)
Range of group IDs to choose from for the
useradd
and
groupadd
programs.
MAIL_DIR (string)
The mail spool directory. This is needed to manipulate the mailbox when its corresponding user account is modified or deleted. If not specified, a compile-time default is used.
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.
PASS_MAX_DAYS, PASS_MIN_DAYS and PASS_WARN_AGE are only used at the time of account creation. Any changes to these settings won't affect existing accounts.
UID_MAX (number), UID_MIN (number)
Range of user IDs to choose from for the
useradd
program.
UMASK (number)
The permission mask is initialized to this value. If not specified, the permission mask will be initialized to 022.
USERDEL_CMD (string)
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).
CROSS REFERENCE
The following cross reference shows which programs in the shadow password suite use which parameters.
Much of the functionality that used to be provided by the shadow password suite is now handled by PAM. Thus,
/etc/login.defs
is no longer used by programs such as:
login(1),
passwd(1),
su(1). Please refer to the corresponding PAM configuration files instead.
