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grantpt(3) — Linux manual page

NAME \|LIBRARY \|SYNOPSIS \|DESCRIPTION \|RETURN VALUE \|ERRORS \|ATTRIBUTES \|STANDARDS \|HISTORY \|SEE ALSO \|COLOPHON

grantpt(3)               Library Functions Manualgrantpt(3)

NAME top

       grantpt - grant access to the slave pseudoterminal

LIBRARY top

       Standard C library (libc,-lc)

SYNOPSIS top

#define _XOPEN_SOURCE#include <stdlib.h>int grantpt(intfd);   Feature Test Macro Requirements for glibc (seefeature_test_macros(7)):grantpt():           Since glibc 2.24:               _XOPEN_SOURCE >= 500           glibc 2.23 and earlier:               _XOPEN_SOURCE

DESCRIPTION top

       Thegrantpt() function changes the mode and owner of the slave       pseudoterminal device corresponding to the master pseudoterminal       referred to by the file descriptorfd.  The user ID of the slave       is set to the real UID of the calling process.  The group ID is       set to an unspecified value (e.g.,tty).  The mode of the slave is       set to 0620 (crw--w----).       The behavior ofgrantpt() is unspecified if a signal handler is       installed to catchSIGCHLDsignals.

RETURN VALUE top

       When successful,grantpt() returns 0.  Otherwise, it returns -1       and setserrno to indicate the error.

ERRORS top

EACCESThe corresponding slave pseudoterminal could not be              accessed.EBADFThefd argument is not a valid open file descriptor.EINVALThefd argument is valid but not associated with a master              pseudoterminal.

ATTRIBUTES top

       For an explanation of the terms used in this section, seeattributes(7).       ┌───────────────────────────────┬───────────────┬────────────────┐       │Interface│Attribute│Value│       ├───────────────────────────────┼───────────────┼────────────────┤       │grantpt()                     │ Thread safety │ MT-Safe locale │       └───────────────────────────────┴───────────────┴────────────────┘

STANDARDS top

       POSIX.1-2008.

HISTORY top

       glibc 2.1.  POSIX.1-2001.       This is part of the UNIX 98 pseudoterminal support, seepts(4).       Historical systems implemented this function via a set-user-ID       helper binary called "pt_chown".  glibc on Linux before glibc 2.33       could do so as well, in order to support configurations with only       BSD pseudoterminals; this support has been removed.  On modern       systems this is either a no-op —with permissions configured on pty       allocation, as is the case on Linux— or anioctl(2).

COLOPHON top

       This page is part of theman-pages (Linux kernel and C library       user-space interface documentation) project.  Information about       the project can be found at        ⟨https://www.kernel.org/doc/man-pages/⟩.  If you have a bug report       for this manual page, see       ⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.       This page was obtained from the tarball man-pages-6.15.tar.gz       fetched from       ⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on       2025-08-11.  If you discover any rendering problems in this HTML       version of the page, or you believe there is a better or more up-       to-date source for the page, or you have corrections or       improvements to the information in this COLOPHON (which isnot       part of the original manual page), send a mail to       man-pages@man7.orgLinux man-pages 6.15            2024-07-23grantpt(3)

Pages that refer to this page:getpt(3), posix_openpt(3), ptsname(3), unlockpt(3), pts(4), pty(7)

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