login(1) USER COMMANDS login(1)
NAME
login - sign on
SYNOPSIS
login [ -d device ] [ name [ environ ... ]]
DESCRIPTION
The login command is used at the beginning of each terminal
session and allows you to identify yourself to the system.
It will be invoked by the system when a connection is first
established. It is invoked by the system when a previous
user has terminated the initial shell by typing a cntrl-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 it is not supplied as an
argument), and if appropriate, your password. Echoing is
turned off (where possible) during the typing of your pass-
word, so it will not appear on the written record of the
session.
If there are no lower-case characters in the first line of
input processed, login assumes the connecting TTY is an
upper-case-only terminal and sets the port's termio(7)
options to reflect this.
login accepts a device option, device. device is taken to
be the path name of the TTY port login is to operate on.
The use of the device option can be expected to improve
login performance, since login will not need to call
ttyname(3).
If you make any mistake in the login procedure, the message
Login incorrect
is printed and a new login prompt will appear. If you make
five incorrect login attempts, all five may be logged in
/var/adm/loginlog (if it exists) and the TTY line will be
dropped.
If you do not complete the login successfully within a cer-
tain period of time (e.g., one minute), you are likely to be
silently disconnected.
After a successful login, accounting files are updated, the
/etc/profile script is executed, the time you last logged in
is printed, /etc/motd is printed, the user-ID, group-ID,
supplementary group list, working directory, and command
interpreter (usually sh) are initialized, and the file
1
login(1) USER COMMANDS login(1)
.profile in the working directory is executed, if it exists.
The name of the command interpreter is - followed by the
last component of the interpreter's path name (e.g., -sh).
If this field in the password file is empty, then the
default command interpreter, /usr/bin/sh is used. If this
field is *, then the named directory becomes the root direc-
tory, 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 /var/adm/login and /etc/passwd.
The basic environment is initialized to:
HOME=your-login-directory
LOGNAME=your-login-name
PATH=/usr/bin
SHELL=last-field-of-passwd-entry
MAIL=/var/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 in 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. login understands
simple single-character quoting conventions. Typing a
backslash in front of a character quotes it and allows the
inclusion of such characters as spaces and tabs.
FILES
/var/adm/utmp accounting
/var/adm/wtmp accounting
/var/mail/your-name mailbox for user your-name
/var/adm/loginlog record of failed login attempts
/etc/default/login default system .login file
/etc/motd message-of-the-day
/etc/passwd password file
/etc/profile system profile
.profile user's login profile
/var/adm/lastlog time of last login
SEE ALSO
mail(1), newgrp(1M), sh(1), su(1M).
2
login(1) USER COMMANDS login(1)
loginlog(4), passwd(4), profile(4), environ(5) in the
Programmer'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: con-
sult a system engineer.
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 a shell
other than the initial shell.
3