NAME
login - sign on

SYNOPSIS
login [ -p ] [ username ]
login [ -p ] [ -h hostname ] [ -f ] [ username ]

DESCRIPTION
The login command is used when a user initially signs on. It may
also be used at any time to change from one user to another. This
case is the one summarized first above and described here. See
"How to Get Started" (in the MachTen User’s Guide) for how to
connect initially. The invocation of login for initial sign-on is
made by a system program or server using the latter form of the
command and is described below.

If login is invoked without an argument, it asks for a user name,
and, if appropriate, a password. Echoing is turned off (if
possible) during the typing of the password, so it will not appear
on the written record of the session.

After a successful login, accounting files are updated and the user
is informed of the existence of mail. The message of the day is
printed, as is the time of his last login. Both are suppressed if
he has a ".hushlogin" file in his home directory; this is mostly
used to make life easier for non-human users, such as uucp.

Login initializes the user and group IDs and the working directory,
then executes a command interpreter (usually csh(1)) according to
specifications found in a password file. Argument 0 of the command
interpreter is the name of the command interpreter with a leading
dash ("-").

Login also modifies the environment environ(7) with information
specifying home directory, command interpreter, terminal type (if
available) and user name. The ‘-p’ argument causes the remainder
of the environment to be preserved, otherwise any previous
environment is discarded.

If the file /etc/nologin exists, login prints its contents on the
user’s terminal and exits, (root is still let in). This is used by
shutdown(8) to stop users logging in when the system is about to go
down.

Login is recognized by sh(1) and csh(1) and executed directly
(without forking).

There are several additional options to login for use at initial
login. With one exception, these options are available only to the
superuser. The -h option is used by telnetd(8) and other servers
to list the host from which the connection was received. The -f
option is used with a username on the command line to indicate that
proper authentication has already been done and that no password
need be requested. This option may be used by the superuser or by
the user specified on the command line.

FILES
/etc/utmp accounting
/usr/adm/wtmp accounting
/usr/spool/mail/* mail
/etc/motd message-of-the-day
/etc/passwd password file
/etc/nologin stops logins
.hushlogin makes login quieter

SEE ALSO
mail(1), passwd(1), rlogin(1), getpass(3), passwd(5), utmp(5),
environ(7), init(8), getty(8), shutdown(8)

DIAGNOSTICS
"Login incorrect," if the name or the password is bad.
"No Shell", "cannot open password file", "no directory"

BUGS
An undocumented option, -r is used by the remote login server,
rlogind(8) to force login to enter into an initial connection
protocol.