LOGIN(1) (Essential Utilities) LOGIN(1)
NAME
login - sign on
SYNOPSIS
login [ name [ env-var ... ]]
DESCRIPTION
The login command is used at the beginning of each terminal
session and allows you to identify yourself to the system.
It may be invoked as a command or by the system when a
connection is first established. Also, it is invoked by the
system when a previous user has terminated the initial shell
by typing a ctrl-d to indicate an "end-of-file."
If login is invoked as a command, it must replace the
initial command interpreter. This is accomplished by
typing:
exec login
from the initial shell.
login asks for your user name (if not supplied as an
argument) 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.
If you make any mistake in the login procedure, you will
receive the message
Login incorrect
and a new login prompt will appear. If you make five
incorrect login attempts, all five may be logged in
/usr/adm/loginlog (if it exists) and the line will be
dropped.
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.
After a successful login, accounting files are updated, the
procedure /etc/profile is performed, the message-of-the-day,
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LOGIN(1) (Essential Utilities) LOGIN(1)
if any, is printed, the user-ID, the group-ID, the working
directory, and the command interpreter [usually sh(1)] is
initialized, and the file .profile in the working directory
is executed, if it exists. These specifications are found
in the /etc/passwd file entry for the user. The name of the
command interpreter is - followed by the last component of
the interpreter's path name (i.e., -sh). If this field in
the password file is empty, then the default command
interpreter, /bin/sh is used. If this field is *, then the
named directory becomes the root directory, the starting
point for path searches for path names beginning with a /.
At that point, login is re-executed at the new level which
must have its own root structure, including /etc/login and
/etc/passwd.
The basic environment is initialized to:
HOME=your-login-directory
PATH=:/bin:/usr/bin
SHELL=last-field-of-passwd-entry
MAIL=/usr/mail/your-login-name
TZ=timezone-specification
The environment may be expanded or modified by supplying
additional arguments to login, either at execution time or
when login requests your login name. The arguments may take
either the form xxx or xxx=yyy. Arguments without an equal
sign are placed in the environment as
Ln=xxx
where n is a number starting at 0 and is incremented each
time a new variable name is required. Variables containing
an = are placed into the environment without modification.
If they already appear in the environment, then they replace
the older value. There are two exceptions. The variables
PATH and SHELL cannot be changed. This prevents people,
logging into restricted shell environments, from spawning
secondary shells which are not restricted. Both login and
getty understand simple single-character quoting
conventions. Typing a backslash in front of a character
quotes it and allows the inclusion of such things as spaces
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and tabs.
FILES
/etc/utmp accounting
/etc/wtmp accounting
/usr/mail/your-name mailbox for user your-name
/usr/adm/loginlog record of failed login attempts
/etc/motd message-of-the-day
/etc/passwd password file
/etc/shadow shadow password file
/etc/profile system profile
.profile user's login profile
SEE ALSO
mail(1), newgrp(1), sh(1), su(1M).
loginlog(4), passwd(4), profile(4), environ(5) in the System
Administrator's Reference Manual.
DIAGNOSTICS
login incorrect if the user name or the password cannot be
matched.
No shell, cannot open password file, or no directory:
consult a UNIX system programming counselor.
No utmp entry. You must exec "login" from the lowest level
"sh" if you attempted to execute login as a command without
using The shell's exec internal command or from other than
the initial shell.
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