SysIII/usr/src/man/man1/login.1

.TH LOGIN 1
.SH NAME
login \- sign on
.SH DESCRIPTION
The
.I login\^
command
is used at the beginning of each terminal session
and allows you to identify yourself to the system.
It can no longer be invoked explicitly,
but is invoked by the system when a connection
is first established,
or after the previous user has logged out by sending
an ``end-of-file'' (control\-D) to his or her initial shell.
(See
.I "How to Get Started\^"
at the beginning of this volume
for instructions on how to dial up initially.)
.PP
.I Login\^
asks for your user name, and, if
appropriate, your password.
Echoing is turned off (where possible) during the typing of your password,
so it will not appear on the written record of the
session.
.PP
At some installations, an option may be invoked that will require
you to enter a second ``external'' password.
This will occur only
for dial-up connections, and will be prompted by the message
``External security:''.
Both passwords are required for a successful login.
.PP
If password aging has been invoked by the super-user on your behalf,
your password may have expired.
In this case, you will be shunted 
into
.IR passwd (1)
to change it, after which you may attempt to login again.
.PP
If you do not complete the login successfully within a
certain period of time (e.g.,
one minute), you are likely to be silently disconnected.
.PP
After a successful login,
accounting files are updated,
you will be informed of the
existence (if any) of
mail,
and the profiles
(i.e.,
.BR /etc/profile " and " \s-1$HOME\s+1/.profile )
(if any) are executed
(see
.IR profile (5)).
.I Login\^
initializes the user and group \s-1ID\s+1s and the working directory,
then executes a command interpreter (usually
.IR sh (1))
according to specifications found in
the
.B /etc/passwd
file.
Argument 0 of the command interpreter is
.B \-
followed by the last component of the interpreter's path name.
The
.I environment\^
(see
.IR environ (7))
is initialized to:
.RS
.RI \s-1HOME\s+1= your-login-directory\^
.br
\s-1PATH\s+1=:/bin:/usr/bin
.br
.RI \s-1LOGNAME\s+1= your-login-name\^
.RE
.SH FILES
.ta \w'/usr/mail/your-name  'u
/etc/utmp	accounting
.br
/usr/adm/wtmp	accounting
.br
.RI /usr/mail/ your-name "	mailbox for user\^"
.I your-name\^
.br
/etc/motd	message-of-the-day
.br
/etc/passwd	password file
.br
/etc/profile	system profile
.br
\s-1$HOME\s+1/\s+4.\s-4profile	personal profile
.DT
.SH SEE ALSO
mail(1),
newgrp(1),
sh(1),
passwd(1),
su(1),
passwd(5),
profile(5),
environ(7),
getty(8).
.SH DIAGNOSTICS
.PD 0
.TP
.I "Login incorrect\^"
if the user name or the password is incorrect.
.TP
.IR "No shell" ", " "cannot open password file" ", " "no directory" :
consult a
.SM UNIX 
programming counselor.
.TP
.IR "Your password has expired" ". " "Choose a new one" .
if password aging is implemented.
.PD