grantpt(3p) — Linux manual page

GRANTPT(3P)             POSIX Programmer's Manual             GRANTPT(3P)

PROLOG         top

       This manual page is part of the POSIX Programmer's Manual.  The
       Linux implementation of this interface may differ (consult the
       corresponding Linux manual page for details of Linux behavior), or
       the interface may not be implemented on Linux.

NAME         top

       grantpt — grant access to the slave pseudo-terminal device

SYNOPSIS         top

       #include <stdlib.h>

       int grantpt(int fildes);

DESCRIPTION         top

       The grantpt() function shall change the mode and ownership of the
       slave pseudo-terminal device associated with its master pseudo-
       terminal counterpart. The fildes argument is a file descriptor
       that refers to a master pseudo-terminal device. The user ID of the
       slave shall be set to the real UID of the calling process and the
       group ID shall be set to an unspecified group ID. The permission
       mode of the slave pseudo-terminal shall be set to readable and
       writable by the owner, and writable by the group.

       The behavior of the grantpt() function is unspecified if the
       application has installed a signal handler to catch SIGCHLD
       signals.

RETURN VALUE         top

       Upon successful completion, grantpt() shall return 0; otherwise,
       it shall return -1 and set errno to indicate the error.

ERRORS         top

       The grantpt() function may fail if:

       EACCES The corresponding slave pseudo-terminal device could not be
              accessed.

       EBADF  The fildes argument is not a valid open file descriptor.

       EINVAL The fildes argument is not associated with a master pseudo-
              terminal device.

       The following sections are informative.

EXAMPLES         top

       None.

APPLICATION USAGE         top

       None.

RATIONALE         top

       See the RATIONALE section for posix_openpt(3p).

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       open(3p), posix_openpt(3p), ptsname(3p), unlockpt(3p)

       The Base Definitions volume of POSIX.1‐2017, stdlib.h(0p)

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic
       form from IEEE Std 1003.1-2017, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The
       Open Group Base Specifications Issue 7, 2018 Edition, Copyright
       (C) 2018 by the Institute of Electrical and Electronics Engineers,
       Inc and The Open Group.  In the event of any discrepancy between
       this version and the original IEEE and The Open Group Standard,
       the original IEEE and The Open Group Standard is the referee
       document. The original Standard can be obtained online at
       http://www.opengroup.org/unix/online.html .

       Any typographical or formatting errors that appear in this page
       are most likely to have been introduced during the conversion of
       the source files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group                2017                       GRANTPT(3P)

Pages that refer to this page: stdlib.h(0p),  posix_openpt(3p),  ptsname(3p),  unlockpt(3p)

HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH.