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OPENPTY(3) BSD Library Functions Manual
OPENPTY(3)
openpty
,
login_tty
,
forkpty
-- tty utility functions
SYNOPSIS
#include
<util.h>
openpty
(
int
*amaster
,
int
*aslave
,
char
*name
,
struct
termios
*termp
,
struct
winsize
*winp
);
login_tty
(
int
fd
);
pid
_
t
forkpty
(
int
*amaster
,
char
*name
,
struct
termios
*termp
,
struct
winsize
*winp
);
DESCRIPTION
The
openpty
(),
login_tty
(), and
forkpty
() functions perform manipulations
on ttys and pseudo-ttys.
The
openpty
() function finds an available pseudo-tty and returns file
descriptors for the master and slave in
amaster
and
aslave
. If
name
is
non-null, the filename of the slave is returned in
name
. If
termp
is
non-null, the terminal parameters of the slave will be set to the values
in
termp
. If
winp
is non-null, the window size of the slave will be set
to the values in
winp
.
The
login_tty
() function prepares for a login on the tty
fd
(which may be
a real tty device, or the slave of a pseudo-tty as returned by
openpty
())
by creating a new session, making
fd
the controlling terminal for the
current process, setting
fd
to be the standard input, output, and error
streams of the current process, and closing
fd
.
The
forkpty
() function combines
openpty
(),
fork
(), and
login_tty
() to
creates a new process operating in a pseudo-tty. The file descriptor of
the master side of the pseudo-tty is returned in
amaster
, and the file-
name filename
name of the slave in
name
if it is non-null. The
termp
and
winp
parame-
ters, parameters,
ters, if non-null, will determine the terminal attributes and window size
of the slave side of the pseudo-tty.
RETURN
VALUES
If a call to
openpty
(),
login_tty
(), or
forkpty
() is not successful, -1
is returned and
errno
is set to indicate the error. Otherwise,
openpty
(),
login_tty
(), and the child process of
forkpty
() return 0, and
the parent process of
forkpty
() returns the process ID of the child
process.
ERRORS
openpty
() will fail if:
[ENOENT] There are no available ttys.
login_tty
() will fail if
ioctl
() fails to set
fd
to the controlling ter-
minal terminal
minal of the current process.
forkpty
() will fail if either
openpty
() or
fork
() fails.
FILES
/dev/[pt]ty[pqrstuwxyzPQRST][0123456789abcdef]
SEE
ALSO
fork(2)
The names of the virtual consoles for the i386 PCVT console driver con-
flict conflict
flict with what would be the seventh group of pseudo-ttys, so
openpty
()
skips
/dev/[pt]tyv[0123456789abcdef]
while looking for pseudo-ttys.
BSD November 4, 1996 BSD
