posix_openpt - open a pseudoterminal device
#include <stdlib.h>
#include <fcntl.h>
int posix_openpt(int flags);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
posix_openpt(): _XOPEN_SOURCE >= 600
The
posix_openpt() function opens an unused pseudoterminal master device,
returning a file descriptor that can be used to refer to that device.
The
flags argument is a bit mask that ORs together zero or more of the
following flags:
- O_RDWR
- Open the device for both reading and writing. It is usual to specify this
flag.
- O_NOCTTY
- Do not make this device the controlling terminal for the process.
On success,
posix_openpt() returns a nonnegative file descriptor which is
the lowest numbered unused file descriptor. On failure, -1 is returned, and
errno is set to indicate the error.
See
open(2).
Glibc support for
posix_openpt() has been provided since version 2.2.1.
For an explanation of the terms used in this section, see
attributes(7).
Interface |
Attribute |
Value |
posix_openpt () |
Thread safety |
MT-Safe |
POSIX.1-2001, POSIX.1-2008.
posix_openpt() is part of the UNIX 98 pseudoterminal support (see
pts(4)).
Some older UNIX implementations that support System V (aka UNIX 98)
pseudoterminals don't have this function, but it is easy to implement:
int
posix_openpt(int flags)
{
return open("/dev/ptmx", flags);
}
Calling
posix_openpt() creates a pathname for the corresponding
pseudoterminal slave device. The pathname of the slave device can be obtained
using
ptsname(3). The slave device pathname exists only as long as the
master device is open.
open(2),
getpt(3),
grantpt(3),
ptsname(3),
unlockpt(3),
pts(4),
pty(7)