LOGIN(1)						   Linux Administrator's Manual 						  LOGIN(1)

NAME

       login - Begin session on the system

SYNOPSIS

       login [ -p ] [ -h host ] [ -H ] [ -f username | username ]

DESCRIPTION

       login is used when signing onto a system.  If no argument is given, login prompts for the username.

       The  user is then prompted for a password, where approprate.  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 the account, the user may be prompted for a new password before proceeding. He  will  be	forced	to
       provide his old password and the new password before continuing. Please refer to passwd(1) for more information.

       The  user and group ID will be set according to their values in the file. There is one exception if the user ID is zero: in this case, only
       the primary group ID of the account is set. This should prevent that the system adminitrator cannot login in case of network problems.  The
       value  for  $HOME, $SHELL, $PATH, $LOGNAME, and $MAIL are set according to the appropriate fields in the password entry.  $PATH defaults to
       /usr/local/bin:/bin:/usr/bin:.  for normal users, and to /sbin:/bin:/usr/sbin:/usr/bin for root if not other configured.   The  environment
       variable  $TERM	will  be preserved, if it exists (other environment variables are preserved if the -p option is given) or be initialize to
       the terminal type on your tty line, as specified in /etc/ttytype.

       Then the user's shell is started. If no shell is specified for the user in /etc/passwd, then /bin/sh is used.  If  there  is  no  directory
       specified in /etc/passwd, then / is used (the home directory is checked for the .hushlogin file described above).

       login reads the /etc/login.defs(5) configuration file. Please refer to this documenation for options which could be set.

OPTIONS

       -p     Used by getty(8) to tell login not to destroy the environment

       -f     Used  to	skip  a  second  login authentication. This option is deprecated and should not be used. It does specifically not work for
	      root. Using this option also means, that not all PAM functions are called.

       -h     Used by other servers (i.e., telnetd(8)) to pass the name of the remote host to login so that it may be placed  in  utmp	and  wtmp.
	      Only the superuser may use this option.

       -H     Used by other servers (i.e., telnetd(8)) to tell login that printing the hostname should be suppressed in the login: prompt.

FILES

       /var/run/utmp - list of current login sessins
       /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/login.defs - configuration file

SEE ALSO

       init(8), getty(8), mail(1), passwd(1), passwd(5), environ(7), shutdown(8), login.defs(5)

BUGS

       A  recursive  login,  as  used  to be possible in the good old days, no longer works; for most purposes su(1) is a satisfactory substitute.
       Indeed, for security reasons, login does a vhangup() system call to remove any possible listening processes on the tty. This  is  to  avoid
       password  sniffing.  If	one  uses the command "login", then the surrounding shell gets killed by vhangup() because it's no longer the true
       owner of the tty.  This can be avoided by using "exec login" in a top-level shell or xterm.

AUTHOR

       Derived from BSD login 5.40 (5/9/89) by Michael Glad (glad@daimi.dk) for HP-UX
       Ported to Linux 0.12: Peter Orbaek (poe@daimi.aau.dk)
       Added new features: Thorsten Kukuk (kukuk@suse.de)

PAM Login 3.32							    2. May 2007 							  LOGIN(1)