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30.\"	@(#)login.1	8.2 (Berkeley) 5/5/94
31.\"
32.Dd May 5, 1994
33.Dt LOGIN 1
34.Os
35.Sh NAME
36.Nm login
37.Nd log into the computer
38.Sh SYNOPSIS
39.Nm login
40.Op Fl fp
41.Op Fl h Ar hostname
42.Op Fl L Ar local-ip-address
43.Op Fl R Ar remote-ip-address
44.Op Fl u Ar username
45.Op Ar user
46.Sh DESCRIPTION
47The
48.Nm
49utility logs users (and pseudo-users) into the computer system.
50.Pp
51If no user is specified, or if a user is specified and authentication
52of the user fails,
53.Nm
54prompts for a user name.
55Authentication of users is normally done via passwords, though
56external authentication mechanisms may be used (see
57.Xr login.conf 5 ) .
58To specify the alternate authentication mechanism
59.Va style ,
60the string
61.Li : Ns Va style
62is appended to the user name (i.e.,
63.Ar user Ns Li : Ns Va style ) .
64.Pp
65The options are as follows:
66.Bl -tag -width Ds
67.It Fl f
68The
69.Fl f
70option is used when a user name is specified to indicate that proper
71authentication has already been done and that no password need be
72requested.
73This option may only be used by the superuser or when an already
74logged in user is logging in as themselves.
75.It Fl h Ar hostname
76Specifies the host from which the connection was received.
77This option may only be used by the superuser.
78.It Fl L
79The
80.Fl L
81option specifies the local IP address of a socket.
82This information is passed on to any classify script (see
83.Xr login.conf 5 ) .
84.It Fl p
85By default,
86.Nm
87discards any previous environment.
88The
89.Fl p
90option disables this behavior.
91.It Fl R
92The
93.Fl R
94option specifies the remote IP address of a socket.
95This information is passed on to any classify script (see
96.Xr login.conf 5 ) .
97.It Fl u Ar username
98Specifies the remote user that initiated the connection.
99This option may only be used by the superuser.
100.El
101.Pp
102If the file
103.Pa /etc/nologin
104exists (and the
105.Dq ignorenologin
106boolean is not set in the user's login class),
107.Nm
108displays its contents to the user and exits.
109This is used by
110.Xr shutdown 8
111to prevent users from logging in when the system is about to go down.
112.Pp
113If the file
114.Pa /etc/fbtab
115exists,
116.Nm
117changes the protection and ownership of certain devices specified in this
118file.
119.Pp
120If the file
121.Pa /var/log/failedlogin
122exists,
123.Nm
124will record failed login attempts in this file.
125.Pp
126Immediately after logging a user in,
127.Nm
128displays the system copyright notice, the date and time the user last
129logged in, the date and time of the last unsuccessful login (if the file
130.Pa /var/log/failedlogin
131exists), the message of the day as well as other information.
132If the file
133.Dq Pa .hushlogin
134exists in the user's home directory, all of these messages are suppressed.
135This is to simplify logins for non-human users, such as
136.Xr uucp .
137.Nm
138then records an entry in the
139.Xr wtmp 5
140and
141.Xr utmp 5
142files and executes the user's command interpreter.
143.Pp
144.Nm
145enters information into the environment (see
146.Xr environ 7 )
147specifying the user's home directory
148.Pq Ev HOME ,
149command interpreter
150.Pq Ev SHELL ,
151search path
152.Pq Ev PATH ,
153terminal type
154.Pq Ev TERM ,
155and user name
156.Po both Ev LOGNAME and Ev USER
157.Pc .
158.Pp
159The standard shells,
160.Xr csh 1
161and
162.Xr sh 1 ,
163do not fork before executing the
164.Nm
165utility.
166.Pp
167Note that if
168.Nm
169is invoked by a non-root user, it will execute
170.Xr su 1
171in
172.Nm
173emulation mode instead.
174.Sh ENVIRONMENT
175.Nm
176sets the following environment variables:
177.Bl -tag -width REMOTEHOST
178.It Ev HOME
179The user's home directory, as specified by the password database.
180.It Ev SHELL
181The user's shell, as specified by the password database.
182.It Ev TERM
183The user's terminal type, if it can be determined.
184.It Ev LOGNAME
185The user's login name.
186.It Ev USER
187Same as
188.Ev LOGNAME .
189.It Ev REMOTEHOST
190The name of the host from which the user logged in, if the
191.Fl h
192flag was specified.
193.It Ev REMOTEUSER
194The name of the remote user who initiated the connection, if the
195.Fl u
196flag was specified.
197.El
198.Pp
199Other environment variables may be specified in
200.Pa /etc/login.conf
201via the
202.Dq setenv
203capability.
204.Sh FILES
205.Bl -tag -width /var/log/failedlogin -compact
206.It Pa /etc/fbtab
207changes device protections
208.It Pa /etc/login.conf
209login configuration
210.It Pa /etc/motd
211message-of-the-day
212.It Pa /etc/nologin
213disallows logins
214.It Pa /var/run/utmp
215current logins
216.It Pa /var/log/failedlogin
217failed login account records
218.It Pa /var/log/lastlog
219last login account records
220.It Pa /var/log/wtmp
221login account records
222.It Pa /var/mail/user
223system mailboxes
224.It Pa \&.hushlogin
225makes login quieter
226.El
227.Sh SEE ALSO
228.Xr chpass 1 ,
229.Xr passwd 1 ,
230.Xr su 1 ,
231.Xr telnet 1 ,
232.Xr getpass 3 ,
233.Xr setusercontext 3 ,
234.Xr fbtab 5 ,
235.Xr login.conf 5 ,
236.Xr utmp 5 ,
237.Xr environ 7
238.Sh HISTORY
239A
240.Nm
241utility appeared in
242.At v3 .
243