V8/usr/man/man8/login.8

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.TH LOGIN 8 
.SH NAME
login \- sign on
.SH SYNOPSIS
.B /etc/login
name
.br
.B /etc/login
.B \-f
name
.br
.B /etc/login
.B \-p
passwd-line
.SH DESCRIPTION
.I Login
is executed by
.IR getty (8).
See `How to Get Started' for how to dial up initially.
.PP
.I Login
asks for a password if appropriate.
Echoing is turned off during the typing of the password.
The
.B \-f
option forces login of the named user, without a password.
.B \-p
is similar to
.B \-f
but uses the supplied line of the password file instead of
the appropriate one in
.IR /etc/passwd .
Both of these options will demand a typed password if the named user
is the super-user.
.PP
After a successful login,
accounting files are updated,
the message of the day is printed,
and the user is informed of the
existence of mail. 
.I Login
initializes the user and group IDs and the working directory,
then executes a command interpreter (usually
.IR  sh (1))
according to specifications found in
.IR /etc/passwd .
Argument 0 of the command interpreter is the name of the command interpreter with
a leading dash (`\-') prepended.
.PP
.I Login
also initializes the
environment
with information specifying home directory, search path,
and an indication of the source of the login if appropriate.
.PP
Only the super-user may execute
.IR login .
.SH FILES
.ta \w'/usr/spool/mail/*\ \ 'u
/etc/utmp	accounting
.br
/usr/adm/wtmp	accounting
.br
/usr/spool/mail/*	mail
.br
/etc/motd	message-of-the-day
.br
/etc/passwd	password file
.SH "SEE ALSO"
init(8), newgrp(1), getty(8), su(8), passwd(1)
.SH DIAGNOSTICS
`Login incorrect,'
if the name or the password is bad.
.br
`No Shell', `cannot open password file', `no directory':
seek knowledgeable assistance.