Ausam/doc/man/man2/connect.2

.th CONNECT II APR/79
.sh NAME
connect \*- connect tty ports together
.sh SYNOPSIS
(connect = 59.; not in assembler)
.br
(master-fd in r0)
.br
(slave-fd  in r1)
.br
.ft B
sys connect; type; cntrl-char
.s3
connect(m-fd, s-fd, cchar)
.br
ttyview(m-fd, s-fd, cchar)
.br
ttygrab(m-fd, s-fd, cchar)
.br
disconnect(fd)
.ft R
.sh DESCRIPTION
This call is restricted to the super user.
The two ttys referred to by
.it master-fd
and
.it slave-fd
(file descriptors returned by open) are connected.
The type of connection (or disconnection) is determined by
.it type
above. The meanings for
.it type
are as follows
.s3
.lp +10 5
\fB0\fR	Disconnect.
.it M-fd
and
.it s-fd
must refer to the same tty and it must be currently connected
(it may be either master or slave). The connected terminal and
.it tty
are disconnected.
.s3
.lp +10 5
\fB1\fR	Ordinary connect (log). The two ttys referred to by
.it m-fd
and
.it s-fd
are connected such that any input to either is directed to the
output of the other. Thus a character typed at one of the ttys
will be output at the other. This is primarily for inter-system
communication, as this interchange is performed at interrupt time.
.s3
.lp +10 5
\fB2\fR	View. The master terminal (\fIm-fd\fR) receives a copy of
all output directed to the slave terminal (\fIs-fd\fR). Input typed
at the slave whilst it is in non-ECHO mode is also copied at the master.
Characters typed at the master terminal behave as if they were typed at the
slave. This includes all special characters (such as DEL).
.s3
.lp +10 5
\fB3\fR	Grab. The slave terminal is disconnected from the system and the
master assumes its place. All input from the master appears to come from
the slave, and all output directed to the slave is redirected to the master.
.s3
.i0
For the cases connect, view and grab above,
.it m-fd
and
.it s-fd
must refer to separate ttys, and neither of these may be already connected.
.s3
.it Cchar
is the master control character. When this character is typed at the master
terminal then redirection of that master-slave pair is terminated, and
the connect call returns. A \fIdisconnect\fR call made elsewhere will also
have this effect.
.sh "SEE ALSO"
log(I), open(II)
.sh DIAGNOSTICS
The c bit is set if an error occurred, a \*-1 value is returned for C.
.it Errno
(or R0) may have the following values.
ENOREDIRECT means that
one of the file descriptors passed referred to a tty not capable of 
redirection.
If either is already redirected (or not redirected for disconnect)
then EREDIRECT is returned.
.sh BUGS
Because the system call cannot be interrupted by signals, disconnect
is the only way to remove an unwanted connection.