posix_openpt(3) — Linux manual page

posix_openpt(3)         Library Functions Manual         posix_openpt(3)

NAME         top

       posix_openpt - open a pseudoterminal device

LIBRARY         top

       Standard C library (libc, -lc)

SYNOPSIS         top

       #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         top

       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         top

       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         top

       See open(2).

ATTRIBUTES         top

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

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

STANDARDS         top

       POSIX.1-2008.

HISTORY         top

       glibc 2.2.1.  POSIX.1-2001.

       It is part of the UNIX 98 pseudoterminal support (see pts(4)).

NOTES         top

       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         top

       open(2), getpt(3), grantpt(3), ptsname(3), unlockpt(3), pts(4),
       pty(7)

Linux man-pages 6.04           2023-03-30                posix_openpt(3)

Pages that refer to this page: getpt(3),  grantpt(3),  ptsname(3),  unlockpt(3),  org.freedesktop.machine1(5),  pty(7)

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