posix_openpt(3)



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 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 version 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 |
       +---------------+---------------+---------+
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 is easy to implement:

           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)

COLOPHON
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       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/.

                                  2020-04-11                   POSIX_OPENPT(3)

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