POSIX_OPENPT(3)                                                         Linux Programmer's Manual                                                        POSIX_OPENPT(3)

NAME
       posix_openpt - open a pseudoterminal device

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).

VERSIONS
       Glibc support for posix_openpt() has been provided since version 2.2.1.

ATTRIBUTES
       For an explanation of the terms used in this section, see attributes(7).

       ┌──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┬───────────────┬─────────┐
       │Interface                                                                                                                             │ Attribute     │ Value   │
       ├──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┼───────────────┼─────────┤
       │posix_openpt()                                                                                                                        │ Thread safety │ MT-Safe │
       └──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┴───────────────┴─────────┘

CONFORMING TO
       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  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)

                                                                               2021-03-22                                                                POSIX_OPENPT(3)