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LOGIN(1)		  BSD General Commands Manual		      LOGIN(1)

     login -- authenticate users and set up their session environment

     login [-Ffps] [-a address]	[-h hostname] [user]

     The login utility logs users (and pseudo-users) into the computer system.

     If	no user	is specified, or if a user is specified	and authentication of
     the user fails, login prompts for a user name.  Authentication of users
     is	done via passwords.  If	the user can be	authenticated via S/Key, then
     the S/Key challenge is incorporated in the	password prompt.  The user
     then has the option of entering their Kerberos or normal password or the
     S/Key response.  Neither will be echoed.

     The options are as	follows:

     -a	     The -a option specifies the address of the	host from which	the
	     connection	was received.  It is used by various daemons such as
	     telnetd(8).  This option may only be used by the super-user.

     -F	     The -F option acts	like the -f option, but	also indicates to
	     login that	it should attempt to rewrite an	existing Kerberos 5
	     credentials cache (specified by the KRB5CCNAME environment	vari-
	     able) after dropping permissions to the user logging in.  This
	     flag is not supported under pam(8).

     -f	     The -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

     -h	     The -h option specifies the host from which the connection	was
	     received.	It is used by various daemons such as telnetd(8).
	     This option may only be used by the super-user.

     -p	     By	default, login discards	any previous environment.  The -p op-
	     tion disables this	behavior.

     -s	     Require a secure authentication mechanism like Kerberos or	S/Key
	     to	be used.  This flag is not supported under pam(8).

     If	a user other than the superuser	attempts to login while	the file
     /etc/nologin exists, login	displays its contents to the user and exits.
     This is used by shutdown(8) to prevent normal users from logging in when
     the system	is about to go down.

     Immediately after logging a user in, login	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	".hushlogin" exists in the
     user's home directory, all	of these messages are suppressed.  This	is to
     simplify logins for non-human users.  login then records an entry in the
     wtmp(5) and utmp(5) files,	executes site-specific login commands via the
     ttyaction(3) facility with	an action of "login", and executes the user's
     command interpreter.

     login enters information into the environment (see	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).

     The user's	login experience can be	customized using login class capabili-
     ties as configured	in /etc/login.conf and documented in login.conf(5).

     The standard shells, csh(1) and sh(1), do not fork	before executing the
     login utility.

     /etc/login.conf	login class capability database
     /etc/motd		message-of-the-day
     /etc/nologin	disallows non-superuser	logins
     /var/run/utmp	list of	current	logins
     /var/log/lastlog	last login account records
     /var/log/wtmp	login account records
     /var/mail/user	system mailboxes
     .hushlogin		makes login quieter

     chpass(1),	newgrp(1), passwd(1), rlogin(1), skey(1), getpass(3),
     ttyaction(3), login.conf(5), passwd.conf(5), utmp(5), environ(7),
     kerberos(8), pam(8)

     A login appeared in Version 6 AT&T	UNIX.

     S/Key is a	trademark of Bellcore.

BSD			       November	19, 2008			   BSD


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