grantpt(3) - Linux man page

Name

grantpt - grant access to the slave pseudo-terminal

Synopsis

#define _XOPEN_SOURCE
#include <stdlib.h>
int grantpt(int fd);

Description

The grantpt() function changes the mode and owner of the slave pseudo-terminal device (pty) corresponding to the master pty 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 pty 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 pty.

Conforming to

POSIX.1-2001

Notes

This is part of the Unix98 pty support, see pts(4). Many systems implement this function via a set-user-ID helper binary called "pt_chown". With Linux devpts no such helper binary is required.

Referenced By

getpt(3), pt_chown(5)