OpenBSD-4.6/usr.bin/login/login.1

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.\"	$OpenBSD: login.1,v 1.27 2007/05/31 19:20:12 jmc Exp $
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.\"	@(#)login.1	8.2 (Berkeley) 5/5/94
.\"
.Dd $Mdocdate: May 31 2007 $
.Dt LOGIN 1
.Os
.Sh NAME
.Nm login
.Nd log into the computer
.Sh SYNOPSIS
.Nm login
.Op Fl fp
.Op Fl h Ar hostname
.Op Fl L Ar local-addr
.Op Fl R Ar remote-addr
.Op Fl u Ar username
.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 normally done via passwords, though
external authentication mechanisms may be used (see
.Xr login.conf 5 ) .
To specify the alternate authentication mechanism
.Va style ,
the string
.Li : Ns Va style
is appended to the user name (i.e.,
.Ar user Ns Li : Ns Va style ) .
.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 superuser or when an already
logged in user is logging in as themselves.
.It Fl h Ar hostname
Specifies the host from which the connection was received.
This option may only be used by the superuser.
.It Fl L Ar local-addr
The
.Fl L
option specifies the local address of a socket.
This information is passed on to any classify script (see
.Xr login.conf 5 ) .
.It Fl p
By default,
.Nm
discards any previous environment.
The
.Fl p
option disables this behavior.
.It Fl R Ar remote-addr
The
.Fl R
option specifies the remote address of a socket.
This information is passed on to any classify script (see
.Xr login.conf 5 ) .
.It Fl u Ar username
Specifies the remote user that initiated the connection.
This option may only be used by the superuser.
.El
.Pp
If the file
.Pa /etc/nologin
exists (and the
.Dq ignorenologin
boolean is not set in the user's login class),
.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/fbtab
exists,
.Nm
changes the protection and ownership of certain devices specified in this
file.
.Pp
If the file
.Pa /var/log/failedlogin
exists,
.Nm
will record failed login attempts in this file.
.Pp
Immediately after logging a user in,
.Nm
displays the system copyright notice, the date and time the user last
logged in, the date and time of the last unsuccessful login (if the file
.Pa /var/log/failedlogin
exists), 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 .
.Nm
then records an entry in the
.Xr wtmp 5
and
.Xr utmp 5
files and executes the user's command interpreter.
.Pp
.Nm
enters information into the environment (see
.Xr environ 7 )
specifying the user's home directory
.Pq Ev HOME ,
command interpreter
.Pq Ev SHELL ,
search path
.Pq Ev PATH ,
terminal type
.Pq Ev TERM ,
and user name
.Po both Ev LOGNAME and Ev USER
.Pc .
.Pp
The standard shells,
.Xr csh 1
and
.Xr sh 1 ,
do not fork before executing the
.Nm
utility.
.Pp
Note that if
.Nm
is invoked by a non-root user, it will execute
.Xr su 1
in
.Nm
emulation mode instead.
.Sh ENVIRONMENT
.Nm
sets the following environment variables:
.Bl -tag -width REMOTEHOST
.It Ev HOME
The user's home directory, as specified by the password database.
.It Ev SHELL
The user's shell, as specified by the password database.
.It Ev TERM
The user's terminal type, if it can be determined.
.It Ev LOGNAME
The user's login name.
.It Ev USER
Same as
.Ev LOGNAME .
.It Ev REMOTEHOST
The name of the host from which the user logged in, if the
.Fl h
flag was specified.
.It Ev REMOTEUSER
The name of the remote user who initiated the connection, if the
.Fl u
flag was specified.
.El
.Pp
Other environment variables may be specified in
.Pa /etc/login.conf
via the
.Dq setenv
capability.
.Sh FILES
.Bl -tag -width /var/log/failedlogin -compact
.It Pa /etc/fbtab
changes device protections
.It Pa /etc/login.conf
login configuration
.It Pa /etc/motd
message-of-the-day
.It Pa /etc/nologin
disallows logins
.It Pa /var/log/failedlogin
failed login account records
.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 /var/run/utmp
current logins
.It Pa \&.hushlogin
makes login quieter
.El
.Sh SEE ALSO
.Xr chpass 1 ,
.Xr passwd 1 ,
.Xr su 1 ,
.Xr telnet 1 ,
.Xr getpass 3 ,
.Xr setusercontext 3 ,
.Xr fbtab 5 ,
.Xr login.conf 5 ,
.Xr utmp 5 ,
.Xr environ 7
.Sh HISTORY
A
.Nm
utility appeared in
.At v3 .