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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | VERSIONS | ATTRIBUTES | CONFORMING TO | NOTES | SEE ALSO | COLOPHON |
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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 the file descriptor 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 5.10 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 2017-09-15 GRANTPT(3)
Pages that refer to this page: getpt(3), posix_openpt(3), ptsname(3), unlockpt(3), pts(4), pty(7)
Copyright and license for this manual page
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