login.1

早期freebsd实现

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.\"	@(#)login.1	8.1 (Berkeley) 6/9/93
.\"
.Dd June 9, 1993
.Dt LOGIN 1
.Os BSD 4
.Sh NAME
.Nm login
.Nd log into the computer
.Sh SYNOPSIS
.Nm login
.Op Fl fp
.Op Fl h Ar hostname
.Op Ar user
.Sh DESCRIPTION
The
.Nm login
utility logs users (and pseudo-users) into the computer system.
.Pp
If no user is specified, or if a user is specified and authentication
of the user fails,
.Nm login
prompts for a user name.
Authentication of users is done via passwords.
.Pp
The options are as follows:
.Bl -tag -width Ds
.It Fl f
The
.Fl f
option is used when a user name is specified to indicate that proper
authentication has already been done and that no password need be
requested.
This option may only be used by the super-user or when an already
logged in user is logging in as themselves.
.It Fl h
The
.Fl h
option specifies the host from which the connection was received.
It is used by various daemons such as
.Xr telnetd  8 .
This option may only be used by the super-user.
.It Fl p
By default,
.Nm login
discards any previous environment.
The
.Fl p
option disables this behavior.
.El
.Pp
If the file
.Pa /etc/nologin
exists,
.Nm login
dislays its contents to the user and exits.
This is used by
.Xr shutdown  8
to prevent users from logging in when the system is about to go down.
.Pp
Immediately after logging a user in,
.Nm login
displays the system copyright notice, the date and time the user last
logged in, the message of the day as well as other information.
If the file
.Dq Pa .hushlogin
exists in the user's home directory, all of these messages are suppressed.
This is to simplify logins for non-human users, such as
.Xr uucp 1 .
.Nm Login
then records an entry in the
.Xr wtmp 5
and
.Xr utmp 5
files and executes the user's command interpretor.
.Pp
Login enters information into the environment (see
.Xr environ 7 )
specifying the user's home directory (HOME), command interpreter (SHELL),
search path (PATH), terminal type (TERM) and user name (both LOGNAME and
USER).
.Pp
The standard shells,
.Xr csh 1
and
.Xr sh 1 ,
do not fork before executing the
.Nm login
utility.
.Sh FILES
.Bl -tag -width /var/mail/userXXX -compact
.It Pa /etc/motd
message-of-the-day
.It Pa /etc/nologin
disallows logins
.It Pa /var/run/utmp
current logins
.It Pa /var/log/wtmp
login account records
.It Pa /var/mail/user
system mailboxes
.It Pa \&.hushlogin
makes login quieter
.El
.Sh SEE ALSO
.Xr chpass 1 ,
.Xr passwd 1 ,
.Xr rlogin 1 ,
.Xr getpass 3 ,
.Xr utmp 5 ,
.Xr environ 7 ,
.Sh HISTORY
A
.Nm login
appeared in
.At v6 .