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LOGIN
!!!LOGIN
NAME
SYNOPSIS
DESCRIPTION
OPTIONS
CAVEATS
FILES
SEE ALSO
AUTHOR
----
!!NAME


login - Begin session on the system
!!SYNOPSIS


__login__ [[__-p__] [[''username''] [[''ENV=VAR
...'']__
login__ [[__-p__] [[__-h__ ''host''] [[__-f__
''username'']__
login__ [[__-p__] __-r__ ''host''
!!DESCRIPTION


__login__ is used to establish a new session with the
system. It is normally invoked automatically by responding
to the ''login:'' prompt on the user's terminal.
__login__ may be special to the shell and may not be
invoked as a sub-process. Typically, __login__ is treated
by the shell as __exec login__ which causes the user to
exit from the current shell. Attempting to execute
__login__ from any shell but the login shell will produce
an error message.


When invoked from the ''login:'' prompt, the user may
enter environmental variables after the username. These
variables are entered in the form __NAME=VALUE__. Not all
variables may be set in the fashion, notably __PATH__,
__HOME__ and __SHELL__. Additionally, __IFS__ may
be inhibited if the user's login shell is
__/bin/sh__.


The user is then prompted for a password, where appropriate.
Echoing is disabled to prevent revealing the password. Only
a small number of password failures are permitted before
__login__ exits and the communications link is
severed.


If password aging has been enabled for your account, you may
be prompted for a new password before proceeding. You will
be forced to provide your old password and the new password
before continuing. Please refer to __passwd__ (1) for
more information.


After a successful login, you will be informed of any system
messages and the presence of mail. You may turn off the
printing of the system message file, ''/etc/motd'', by
creating a zero-length file ''.hushlogin'' in your login
directory. The mail message will be one of ''You have
new mail.____You have mail.__
__No Mail.__
__


Your user and group ID will be set according to their values
in the ''/etc/passwd'' file. The value for __$HOME__,
__$SHELL__, __$PATH__, __$LOGNAME__, and
__$MAIL__ are set according to the appropriate fields in
the password entry. Ulimit, umask and nice values may also
be set according to entries in the GECOS field.


On some installations, the environmental variable
__$TERM__ will be initialize to the terminal type on your
tty line, as specified in ''/etc/ttytype''.


An initialization script for your command interpreter may
also be executed. Please see the appropriate manual section
for more information on this function.


A subsystem login is indicated by the presense of a
!!OPTIONS


__-p__


Preserve environment.


__-f__


Do not perform authentication, user is
preauthenticated.


__-h__


Name of the remote host for this login.


__-r__


Perform autologin protocol for rlogin.


The __-r -h__ and __-f__ options are only used when
__login__ is invoked by root.
!!CAVEATS


This version of __login__ has many compilation options,
only some of which may be in use at any particular
site.


The location of files is subject to differences in system
configuration.
!!FILES


/var/run/utmp - list of current login sessions
/var/log/wtmp - list of previous login sessions
/etc/passwd - user account information
/etc/shadow - encrypted passwords and age information
/etc/motd - system message file
/etc/nologin - prevent non-root users from logging in
/etc/ttytype - list of terminal types
$HOME/.profile - initialization script for default shell
$HOME/.hushlogin - suppress printing of system
messages
!!SEE ALSO


getty(8), mail(1), passwd(1),
sh(1), su(1), login.defs(5),
passwd(5), nologin(5)
!!AUTHOR


Julianne Frances Haugh (jfh@austin.ibm.com)
----
39 pages link to login(1):
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Last edited on Tuesday, June 4, 2002 12:22:17 am by "perry"
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