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)

COLOPHON

       This page is part of release 5.13 of the Linux man-pages project.  A  description  of  the
       project,  information  about  reporting  bugs, and the latest version of this page, can be
       found at https://www.kernel.org/doc/man-pages/.

                                            2021-03-22                            POSIX_OPENPT(3)