4.3BSD/usr/man/man2/vhangup.2

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.\" Copyright (c) 1980 Regents of the University of California.
.\" All rights reserved.  The Berkeley software License Agreement
.\" specifies the terms and conditions for redistribution.
.\"
.\"	@(#)vhangup.2	6.2 (Berkeley) 6/30/85
.\"
.TH VHANGUP 2 "June 30, 1985"
.UC 4
.SH NAME
vhangup \- virtually ``hangup'' the current control terminal
.SH SYNOPSIS
.B vhangup()
.SH DESCRIPTION
.I Vhangup
is used by the initialization process
.IR init (8)
(among others) to arrange that users are given
\*(lqclean\*(rq' terminals at login,
by revoking access of the previous users' processes to the terminal.
To effect this,
.I vhangup
searches the system tables for references to the control terminal
of the invoking process, revoking access permissions
on each instance of the terminal that it finds.
Further attempts to access the terminal by the affected processes
will yield i/o errors (EBADF).
Finally,
a hangup signal (SIGHUP) is sent to the process group of the
control terminal.
.SH SEE ALSO
init (8)
.SH BUGS
Access to
the control terminal via
.B /dev/tty
is still possible.
.PP
This call should be replaced by an automatic mechanism that
takes place on process exit.