grantpt(3) - Linux manual page (original) (raw)
grantpt(3) Library Functions Manual grantpt(3)
NAME top
grantpt - grant access to the slave pseudoterminalLIBRARY top
Standard C library (_libc_, _-lc_)SYNOPSIS top
**#define _XOPEN_SOURCE**
**#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
glibc 2.23 and earlier:
_XOPEN_SOURCEDESCRIPTION top
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.RETURN VALUE top
When successful, **grantpt**() returns 0. Otherwise, it returns -1
and sets _[errno](../man3/errno.3.html)_ to indicate the error.ERRORS top
**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 top
For an explanation of the terms used in this section, see
[attributes(7)](../man7/attributes.7.html).
┌───────────────────────────────┬───────────────┬────────────────┐
│ **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, see [pts(4)](../man4/pts.4.html).
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 an [ioctl(2)](../man2/ioctl.2.html).SEE ALSO top
[open(2)](../man2/open.2.html), [posix_openpt(3)](../man3/posix%5Fopenpt.3.html), [ptsname(3)](../man3/ptsname.3.html), [unlockpt(3)](../man3/unlockpt.3.html), [pts(4)](../man4/pts.4.html), [pty(7)](../man7/pty.7.html)COLOPHON top
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man-pages@man7.orgLinux man-pages 6.10 2024-07-23 grantpt(3)
Pages that refer to this page:getpt(3), posix_openpt(3), ptsname(3), unlockpt(3), pts(4), pty(7)