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).
ATTRIBUTES
For an explanation of the terms used in this section, see attrib-
utes(7).
┌───────────────────────────────────────────┬───────────────┬─────────┐
│ Interface │ Attribute │ Value │
├───────────────────────────────────────────┼───────────────┼─────────┤
│ posix_openpt() │ Thread safety │ MT-Safe │
└───────────────────────────────────────────┴───────────────┴─────────┘
STANDARDS
POSIX.1-2008.
HISTORY
glibc 2.2.1. POSIX.1-2001.
It 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
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.
SEE ALSO
open(2), getpt(3), grantpt(3), ptsname(3), unlockpt(3), pts(4), pty(7)
Linux man-pages 6.7 2023-10-31 posix_openpt(3)
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