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
       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.

RETURN VALUE
       On success, posix_openpt() returns a file descriptor (a nonnegative
       integer) which is the lowest numbered unused file descriptor.  On
       failure, -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
       attributes(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
       implemented 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)