path: root/usr.bin/login/login.1

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.\"	@(#)login.1	8.2 (Berkeley) 5/5/94
.\"	$Id: login.1,v 1.10 1998/01/07 10:42:57 obrien Exp $
.\"
.Dd May 5, 1994
.Dt LOGIN 1
.Os BSD 4
.Sh NAME
.Nm login
.Nd log into the computer
.Sh SYNOPSIS
.Nm
.Op Fl fp
.Op Fl h Ar hostname
.Op Ar user
.Sh DESCRIPTION
The
.Nm
utility logs users (and pseudo-users) into the computer system.
.Pp
If no user is specified, or if a user is specified and authentication
of the user fails,
.Nm
prompts for a user name.
Authentication of users is done via passwords.
.Pp
The options are as follows:
.Bl -tag -width Ds
.It Fl f
The
.Fl f
option is used when a user name is specified to indicate that proper
authentication has already been done and that no password need be
requested.
This option may only be used by the super-user or when an already
logged in user is logging in as themselves.
.It Fl h
The
.Fl h
option specifies the host from which the connection was received.
It is used by various daemons such as
.Xr telnetd  8 .
This option may only be used by the super-user.
.It Fl p
By default,
.Nm
discards any previous environment.
The
.Fl p
option disables this behavior.
.El
.Pp
If the file
.Pa /etc/nologin
exists,
.Nm
displays its contents to the user and exits.
This is used by
.Xr shutdown  8
to prevent users from logging in when the system is about to go down.
.Pp
If the file
.Pa /etc/login.access
exists,
.Nm
checks to see if the user and host pair are specifically allowed or denied
access.
Login access may also be controlled via the login class, which provides
allow and deny records based on time, tty and remote host name.
.Pp
If the file
.Pa /etc/fbtab
exists,
.Nm
changes the protection and ownership of certain devices specified in this
file.
.Pp
If the file
.Pa /etc/skeykeys
exists, 
.Nm
will offer S/key password validation if the user has an entry in the file.
.Pa /etc/skey.access
controls from which hosts and/or networks the use of S/key passwords are
obligated.
.Pp
Immediately after logging a user in,
.Nm
displays the system copyright notice, the date and time the user last
logged in, the message of the day as well as other information.
If the file
.Dq Pa .hushlogin
exists in the user's home directory, all of these messages are suppressed.
This is to simplify logins for non-human users, such as
.Xr uucp 1 .
.Nm Login
then records an entry in the
.Xr wtmp 5
and
.Xr utmp 5
files and executes the user's command interpreter.
.Pp
.Nm Login
enters information into the environment (see
.Xr environ 7 )
specifying the user's home directory (HOME), command interpreter (SHELL),
search path (PATH), terminal type (TERM) and user name (both LOGNAME and
USER).
Other environment variables may be set due to entries in the login
class capabilities database, for the login class assigned in the
user's system passwd record.
The login class also controls the maximum and current process resource
limits granted to a login, process priorities and many other aspects of
a user's login environment.
.Pp
The standard shells,
.Xr csh 1
and
.Xr sh 1 ,
do not fork before executing the
.Nm
utility.
.Sh FILES
.Bl -tag -width /var/mail/userXXX -compact
.It Pa /etc/fbtab
changes device protections
.It Pa /etc/login.access
login access control table
.It Pa /etc/login.conf
login class capabilities database
.It Pa /etc/motd
message-of-the-day
.It Pa /etc/nologin
disallows logins
.It Pa /etc/skey.access
skey password control table
.It Pa /etc/skeykeys
skey password database
.It Pa /var/run/utmp
current logins
.It Pa /var/log/lastlog
last login account records
.It Pa /var/log/wtmp
login account records
.It Pa /var/mail/user
system mailboxes
.It Pa \&.hushlogin
makes login quieter
.It Pa /etc/auth.conf
configure authentication services
.El
.Sh SEE ALSO
.Xr chpass 1 ,
.Xr passwd 1 ,
.Xr rlogin 1 ,
.Xr skey 1 ,
.Xr getpass 3 ,
.Xr fbtab 5 ,
.Xr login.access 5 ,
.Xr login.conf 5 ,
.Xr skey.access 5 ,
.Xr utmp 5 ,
.Xr environ 7 ,
.Xr nologin 8
.Sh HISTORY
A
.Nm
utility appeared in
.At v6 .