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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | VERSIONS | ATTRIBUTES | CONFORMING TO | NOTES | SEE ALSO | COLOPHON |
GRANTPT(3) Linux Programmer's Manual GRANTPT(3)
grantpt - grant access to the slave pseudoterminal
#include <stdlib.h>
int grantpt(int fd);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
grantpt():
Since glibc 2.24:
_XOPEN_SOURCE >= 500 ||
(_XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED)
Glibc 2.23 and earlier:
_XOPEN_SOURCE
The grantpt() function changes the mode and owner of the slave
pseudoterminal device corresponding to the master pseudoterminal
referred to by fd. 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 of grantpt() is unspecified if a signal handler is
installed to catch SIGCHLD signals.
When successful, grantpt() returns 0. Otherwise, it returns -1 and
sets errno appropriately.
EACCES The corresponding slave pseudoterminal could not be accessed.
EBADF The fd argument is not a valid open file descriptor.
EINVAL The fd argument is valid but not associated with a master
pseudoterminal.
grantpt() is provided in glibc since version 2.1.
For an explanation of the terms used in this section, see
attributes(7).
┌──────────┬───────────────┬────────────────┐
│Interface │ Attribute │ Value │
├──────────┼───────────────┼────────────────┤
│grantpt() │ Thread safety │ MT-Safe locale │
└──────────┴───────────────┴────────────────┘
POSIX.1-2001, POSIX.1-2008.
This is part of the UNIX 98 pseudoterminal support, see pts(4).
Many systems implement this function via a set-user-ID helper binary
called "pt_chown". On Linux systems with a devpts filesystem
(present since Linux 2.2), the kernel normally sets the correct
ownership and permissions for the pseudoterminal slave when the
master is opened (posix_openpt(3)), so that nothing must be done by
grantpt(). Thus, no such helper binary is required (and indeed it is
configured to be absent during the glibc build that is typical on
many systems).
open(2), posix_openpt(3), ptsname(3), unlockpt(3), pts(4), pty(7)
This page is part of release 4.12 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/.
GNU 2017-05-03 GRANTPT(3)
Pages that refer to this page: getpt(3), posix_openpt(3), ptsname(3), unlockpt(3), pts(4), pty(7)