| 1 | .\" Copyright (c) 1980 Regents of the University of California. |
| 2 | .\" All rights reserved. The Berkeley software License Agreement |
| 3 | .\" specifies the terms and conditions for redistribution. |
| 4 | .\" |
| 5 | .\" @(#)login.1 6.4 (Berkeley) %G% |
| 6 | .\" |
| 7 | .TH LOGIN 1 "" |
| 8 | .UC 4 |
| 9 | .SH NAME |
| 10 | login \- sign on |
| 11 | .SH SYNOPSIS |
| 12 | .B login |
| 13 | [ |
| 14 | .B \-p |
| 15 | ] [ username ] |
| 16 | .br |
| 17 | .B login |
| 18 | [ |
| 19 | .B \-p |
| 20 | ] [ |
| 21 | .B \-h |
| 22 | hostname |
| 23 | ] [ |
| 24 | .B \-f |
| 25 | ] [ |
| 26 | username |
| 27 | ] |
| 28 | .SH DESCRIPTION |
| 29 | The |
| 30 | .I login |
| 31 | command |
| 32 | is used when a user initially |
| 33 | signs on. |
| 34 | It may also be used at any time to change |
| 35 | from one user to another. |
| 36 | This case is the one summarized first above and described here. |
| 37 | See \*(lqHow to Get Started\*(rq for how to connect initially. |
| 38 | The invocation of |
| 39 | .I login |
| 40 | for initial sign-on |
| 41 | is made by a system program or server using the latter form of the command |
| 42 | and is described below. |
| 43 | .PP |
| 44 | If |
| 45 | .I login |
| 46 | is invoked without an argument, |
| 47 | it asks for a user name, and, if |
| 48 | appropriate, a password. |
| 49 | Echoing is turned off (if possible) during the typing of the password, |
| 50 | so it will not appear on the written record of the |
| 51 | session. |
| 52 | .PP |
| 53 | After a successful login, |
| 54 | accounting files are updated and |
| 55 | the user is informed of the |
| 56 | existence of mail. |
| 57 | The message of the day is printed, |
| 58 | as is the time of his last login. |
| 59 | Both are suppressed if he has a \*(lq.hushlogin\*(rq |
| 60 | file in his home directory; this |
| 61 | is mostly used to make life easier for non-human users, such as |
| 62 | .IR uucp . |
| 63 | .PP |
| 64 | .I Login |
| 65 | initializes the user and group IDs and the working directory, |
| 66 | then executes a command interpreter (usually |
| 67 | .IR csh (1)) |
| 68 | according to specifications found in a password file. |
| 69 | Argument 0 of the command interpreter is |
| 70 | the name of the command interpreter with |
| 71 | a leading dash (\*(lq\-\*(rq). |
| 72 | .PP |
| 73 | Login also modifies the |
| 74 | environment |
| 75 | .IR environ (7) |
| 76 | with information specifying home directory, command interpreter, terminal |
| 77 | type (if available) and user name. |
| 78 | The `\-p' argument causes the remainder of the environment to be preserved, |
| 79 | otherwise any previous environment is discarded. |
| 80 | .PP |
| 81 | If the file /etc/nologin exists, |
| 82 | .I login |
| 83 | prints its contents on the user's terminal and exits. This is |
| 84 | used by |
| 85 | .IR shutdown (8) |
| 86 | to stop users logging in when the system is about to go down. |
| 87 | .PP |
| 88 | Login is recognized by |
| 89 | .IR sh (1) |
| 90 | and |
| 91 | .IR csh (1) |
| 92 | and executed directly (without forking). |
| 93 | .PP |
| 94 | There are several additional options to |
| 95 | .I login |
| 96 | for use at initial login. |
| 97 | With one exception, these options are available only to the superuser. |
| 98 | The |
| 99 | .B \-h |
| 100 | option is used by |
| 101 | .IR telnetd (8C) |
| 102 | and other servers to list the host from which |
| 103 | the connection was received. |
| 104 | The |
| 105 | .B \-f |
| 106 | option is used with a username on the command line |
| 107 | to indicate that proper authentication has already been done |
| 108 | and that no password need be requested. |
| 109 | This option may be used by the superuser |
| 110 | or by the user specified on the command line. |
| 111 | .SH FILES |
| 112 | .ta \w'/usr/spool/mail/*\ \ 'u |
| 113 | /etc/utmp accounting |
| 114 | .br |
| 115 | /usr/adm/wtmp accounting |
| 116 | .br |
| 117 | /usr/spool/mail/* mail |
| 118 | .br |
| 119 | /etc/motd message-of-the-day |
| 120 | .br |
| 121 | /etc/passwd password file |
| 122 | .br |
| 123 | /etc/nologin stops logins |
| 124 | .br |
| 125 | \&.hushlogin makes login quieter |
| 126 | .SH "SEE ALSO" |
| 127 | mail(1), passwd(1), rlogin(1), getpass(3), passwd(5), utmp(5), environ(7), |
| 128 | init(8), getty(8), shutdown(8), |
| 129 | .SH DIAGNOSTICS |
| 130 | \*(lqLogin incorrect,\*(rq |
| 131 | if the name or the password is bad. |
| 132 | .br |
| 133 | \*(lqNo Shell\*(rq, \*(lqcannot open password file\*(rq, |
| 134 | \*(lqno directory\*(rq: |
| 135 | consult a programming counselor. |
| 136 | .SH BUGS |
| 137 | An undocumented option, |
| 138 | .B \-r |
| 139 | is used by the remote login server, |
| 140 | .IR rlogind (8) |
| 141 | to force |
| 142 | .I login |
| 143 | to enter into an initial connection protocol. |