posix_openpt(3) Library Functions Manual posix_openpt(3)
NAME
posix_openpt - open a pseudoterminal device
LIBRARY
Standard C library (libc, -lc)
SYNOPSIS
#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
DESCRIPTION
The posix_openpt() function opens an unused pseudoterminal master de-
vice, returning a file descriptor that can be used to refer to that de-
vice.
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.
RETURN VALUE
On success, posix_openpt() returns a file descriptor (a nonnegative in-
teger) which is the lowest numbered unused file descriptor. On fail-
ure, -1 is returned, and errno is set to indicate the error.
ERRORS
See open(2).
VERSIONS
glibc support for posix_openpt() has been provided since glibc 2.2.1.
ATTRIBUTES
For an explanation of the terms used in this section, see at-
tributes(7).
┌────────────────────────────────────────────┬───────────────┬─────────┐
│Interface │ Attribute │ Value │
├────────────────────────────────────────────┼───────────────┼─────────┤
│posix_openpt() │ Thread safety │ MT-Safe │
└────────────────────────────────────────────┴───────────────┴─────────┘
STANDARDS
POSIX.1-2001, POSIX.1-2008.
posix_openpt() is part of the UNIX 98 pseudoterminal support (see
pts(4)).
NOTES
Some older UNIX implementations that support System V (aka UNIX 98)
pseudoterminals don't have this function, but it can be easily imple-
mented by opening the pseudoterminal multiplexor device:
int
posix_openpt(int flags)
{
return open("/dev/ptmx", flags);
}
Calling posix_openpt() creates a pathname for the corresponding pseu-
doterminal slave device. The pathname of the slave device can be ob-
tained using ptsname(3). The slave device pathname exists only as long
as the master device is open.
SEE ALSO
open(2), getpt(3), grantpt(3), ptsname(3), unlockpt(3), pts(4), pty(7)
Linux man-pages 6.03 2023-02-05 posix_openpt(3)
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