grantpt - grant access to the slave pseudoterminal
int grantpt(int fd);
Feature Test Macro Requirements for glibc (see feature_test_macros
Since glibc 2.24:
_XOPEN_SOURCE >= 500 ||
(_XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED)
Glibc 2.23 and earlier:
() function changes the mode and owner of the slave
pseudoterminal device corresponding to the master pseudoterminal referred to
. 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
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
When successful, grantpt
() returns 0. Otherwise, it returns -1 and sets
- The corresponding slave pseudoterminal could not be accessed.
- The fd argument is not a valid open file descriptor.
- The fd argument is valid but not associated with a master
() is provided in glibc since version 2.1.
For an explanation of the terms used in this section, see attributes
This is part of the UNIX 98 pseudoterminal support, see pts
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
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).