Section (3) grantpt
Name
grantpt — grant access to the slave pseudoterminal
Synopsis
#include <stdlib.h>
int
grantpt( |
int fd) ; |
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DESCRIPTION
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.
RETURN VALUE
When successful, grantpt
()
returns 0. Otherwise, it returns −1 and sets
errno
appropriately.
ERRORS
- 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.
ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7).
Interface | Attribute | Value |
grantpt () |
Thread safety | MT-Safe locale |
NOTES
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).
COLOPHON
This page is part of release 4.16 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/.
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