206 lines
5.6 KiB
Groff
206 lines
5.6 KiB
Groff
.\" $NetBSD: login.1,v 1.30 2008/11/19 17:56:53 ginsbach Exp $
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.\"
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.\" Copyright (c) 1980, 1990, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)login.1 8.2 (Berkeley) 5/5/94
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.\"
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.Dd November 19, 2008
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.Dt LOGIN 1
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.Os
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.Sh NAME
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.Nm login
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.Nd authenticate users and set up their session environment
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.Sh SYNOPSIS
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.Nm
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.Op Fl Ffps
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.Op Fl a Ar address
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.Op Fl h Ar hostname
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.Op Ar user
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.Sh DESCRIPTION
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The
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.Nm
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utility logs users (and pseudo-users) into the computer system.
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.Pp
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If no user is specified, or if a user is specified and authentication
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of the user fails,
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.Nm
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prompts for a user name.
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Authentication of users is done via passwords.
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If the user can be authenticated via
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.Tn S/Key ,
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then the
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.Tn S/Key
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challenge is incorporated in the password prompt.
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The user then has the option of entering their Kerberos or normal
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password or the
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.Tn S/Key
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response.
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Neither will be echoed.
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.Pp
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The options are as follows:
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.Bl -tag -width Ds
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.It Fl a
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The
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.Fl a
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option specifies the address of the host from which the connection was received.
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It is used by various daemons such as
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.Xr telnetd 8 .
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This option may only be used by the super-user.
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.It Fl F
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The
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.Fl F
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option acts like the
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.Fl f
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option, but also indicates to
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.Nm
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that it should attempt to rewrite an existing Kerberos 5 credentials cache
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(specified by the KRB5CCNAME environment variable) after dropping
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permissions to the user logging in.
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This flag is not supported under
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.Xr pam 8 .
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.It Fl f
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The
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.Fl f
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option is used when a user name is specified to indicate that proper
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authentication has already been done and that no password need be
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requested.
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This option may only be used by the super-user or when an already
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logged in user is logging in as themselves.
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.It Fl h
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The
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.Fl h
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option specifies the host from which the connection was received.
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It is used by various daemons such as
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.Xr telnetd 8 .
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This option may only be used by the super-user.
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.It Fl p
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By default,
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.Nm
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discards any previous environment.
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The
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.Fl p
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option disables this behavior.
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.It Fl s
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Require a secure authentication mechanism like
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.Tn Kerberos
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or
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.Tn S/Key
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to be used.
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This flag is not supported under
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.Xr pam 8 .
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.El
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.Pp
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If a user other than the superuser attempts to login while the file
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.Pa /etc/nologin
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exists,
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.Nm
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displays its contents to the user and exits.
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This is used by
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.Xr shutdown 8
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to prevent normal users from logging in when the system is about to go down.
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.Pp
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Immediately after logging a user in,
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.Nm
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displays the system copyright notice, the date and time the user last
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logged in, the message of the day as well as other information.
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If the file
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.Dq Pa .hushlogin
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exists in the user's home directory, all of these messages are suppressed.
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This is to simplify logins for non-human users.
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.Nm
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then records an entry in the
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.Xr wtmp 5
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and
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.Xr utmp 5
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files, executes site-specific login commands via the
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.Xr ttyaction 3
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facility with an action of "login", and executes the user's command
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interpreter.
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.Pp
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.Nm
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enters information into the environment (see
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.Xr environ 7 )
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specifying the user's home directory (HOME), command interpreter (SHELL),
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search path (PATH), terminal type (TERM) and user name (both LOGNAME and
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USER).
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.Pp
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The user's login experience can be customized using
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login class capabilities as configured in
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.Pa /etc/login.conf
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and documented in
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.Xr login.conf 5 .
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.Pp
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The standard shells,
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.Xr csh 1
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and
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.Xr sh 1 ,
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do not fork before executing the
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.Nm
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utility.
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.Sh FILES
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.Bl -tag -width /var/mail/userXXX -compact
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.It Pa /etc/login.conf
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login class capability database
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.It Pa /etc/motd
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message-of-the-day
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.It Pa /etc/nologin
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disallows non-superuser logins
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.It Pa /var/run/utmp
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list of current logins
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.It Pa /var/log/lastlog
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last login account records
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.It Pa /var/log/wtmp
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login account records
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.It Pa /var/mail/user
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system mailboxes
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.It Pa \&.hushlogin
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makes login quieter
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.El
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.Sh SEE ALSO
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.Xr chpass 1 ,
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.Xr newgrp 1 ,
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.Xr passwd 1 ,
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.Xr rlogin 1 ,
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.Xr skey 1 ,
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.Xr getpass 3 ,
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.Xr ttyaction 3 ,
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.Xr login.conf 5 ,
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.Xr passwd.conf 5 ,
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.Xr utmp 5 ,
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.Xr environ 7 ,
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.Xr kerberos 8 ,
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.Xr pam 8
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.Sh HISTORY
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A
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.Nm
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appeared in
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.At v6 .
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.Sh TRADEMARKS AND PATENTS
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.Tn S/Key
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is a trademark of
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.Tn Bellcore .
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