4.3BSD-Tahoe/usr/man/cat1/login.0

LOGIN(1)	    UNIX Programmer's Manual		 LOGIN(1)



NNAAMMEE
     login - sign on

SSYYNNOOPPSSIISS
     llooggiinn [ --pp ] [ username ]
     llooggiinn [ --pp ] [ --hh hostname ] [ --ff ] [ username ]

DDEESSCCRRIIPPTTIIOONN
     The _l_o_g_i_n command is used when a user initially signs on.
     It may also be used at any time to change from one user to
     another.  This case is the one summarized first above and
     described here.  See "How to Get Started" for how to connect
     initially.  The invocation of _l_o_g_i_n for initial sign-on is
     made by a system program or server using the latter form of
     the command and is described below.

     If _l_o_g_i_n is invoked without an argument, it asks for a user
     name, and, if appropriate, a password.  Echoing is turned
     off (if possible) during the typing of the password, so it
     will not appear on the written record of the session.

     After a successful login, accounting files are updated and
     the user is informed of the existence of mail.  The message
     of the day is printed, as is the time of his last login.
     Both are suppressed if he has a ".hushlogin" file in his
     home directory; this is mostly used to make life easier for
     non-human users, such as _u_u_c_p.

     _L_o_g_i_n initializes the user and group IDs and the working
     directory, then executes a command interpreter (usually
     _c_s_h(1)) according to specifications found in a password
     file.  Argument 0 of the command interpreter is the name of
     the command interpreter with a leading dash ("-").

     Login also modifies the environment _e_n_v_i_r_o_n(7) with informa-
     tion specifying home directory, command interpreter, termi-
     nal type (if available) and user name.  The `-p' argument
     causes the remainder of the environment to be preserved,
     otherwise any previous environment is discarded.

     If the file /etc/nologin exists, _l_o_g_i_n prints its contents
     on the user's terminal and exits. This is used by _s_h_u_t_-
     _d_o_w_n(8) to stop users logging in when the system is about to
     go down.

     Login is recognized by _s_h(1) and _c_s_h(1) and executed
     directly (without forking).

     There are several additional options to _l_o_g_i_n for use at
     initial login.  With one exception, these options are avail-
     able only to the superuser.  The --hh option is used by
     _t_e_l_n_e_t_d(8C) and other servers to list the host from which



Printed 7/9/88	       September 14, 1987			1






LOGIN(1)	    UNIX Programmer's Manual		 LOGIN(1)



     the connection was received.  The --ff option is used with a
     username on the command line to indicate that proper authen-
     tication has already been done and that no password need be
     requested.  This option may be used by the superuser or by
     the user specified on the command line.

FFIILLEESS
     /etc/utmp		accounting
     /usr/adm/wtmp	accounting
     /usr/spool/mail/*	mail
     /etc/motd		message-of-the-day
     /etc/passwd	password file
     /etc/nologin	stops logins
     .hushlogin         makes login quieter

SSEEEE AALLSSOO
     mail(1), passwd(1), rlogin(1), getpass(3), passwd(5),
     utmp(5), environ(7), init(8), getty(8), shutdown(8),

DDIIAAGGNNOOSSTTIICCSS
     "Login incorrect," if the name or the password is bad.
     "No Shell", "cannot open password file", "no directory":
     consult a programming counselor.

BBUUGGSS
     An undocumented option, --rr is used by the remote login
     server, _r_l_o_g_i_n_d(8) to force _l_o_g_i_n to enter into an initial
     connection protocol.



























Printed 7/9/88	       September 14, 1987			2