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grantpt(3) [bsd man page]

GRANTPT(3)						     Linux Programmer's Manual							GRANTPT(3)

grantpt - grant access to the slave pseudoterminal SYNOPSIS
#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 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. VERSIONS
grantpt() is provided in glibc since version 2.1. ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7). +----------+---------------+----------------+ |Interface | Attribute | Value | +----------+---------------+----------------+ |grantpt() | Thread safety | MT-Safe locale | +----------+---------------+----------------+ CONFORMING TO
POSIX.1-2001, POSIX.1-2008. 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). SEE ALSO
open(2), posix_openpt(3), ptsname(3), unlockpt(3), pts(4), pty(7) COLOPHON
This page is part of release 4.15 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 GNU
2017-09-15 GRANTPT(3)

Check Out this Related Man Page

grantpt(3)						     Library Functions Manual							grantpt(3)

grantpt - Permits access to the slave pseudoterminal device LIBRARY
Standard C Library (, libc.a) SYNOPSIS
#include <stdlib.h> int grantpt( int fildes); STANDARDS
Interfaces documented on this reference page conform to industry standards as follows: grantpt(): XPG4-UNIX Refer to the standards(5) reference page for more information about industry standards and associated tags. PARAMETERS
Specifies a file descriptor that is returned from a successful open of a master pseudoterminal device. DESCRIPTION
The grantpt() function modifies the ownership and mode of the slave pseudoterminal device associated with its master pseudoterminal coun- terpart. The modifications of mode and ownership are performed as follows: The group ID is set to a reserved group. The slave user ID is set to the real UID of the calling process. The permissions of the slave device are set so that the owner is allowed read and write access and the group is allowed write access. RETURN VALUES
Upon successful completion, the grantpt() function returns a value of 0 (zero). Otherwise, it returns a value of -1 and sets errno to indi- cate the error. ERRORS
The grantpt() function sets errno to the specified values for the following conditions: The corresponding slave device cannot be accessed. The file descriptor specified by the fildes parameter is not a valid open file descrip- tor. The file descriptor specified by the fildes parameter is not associated with a master device. The grantpt() function may also fail if the application has installed a signal handler to catch SIGCHLD (death of a child) signals. Applications calling grantpt() may get a SIGCHLD signal from processes that they did not explicitly create. RELATED INFORMATION
Functions: open(2), ptsname(3), setuid(2), unlockpt(3) Standards: standards(5) delim off grantpt(3)

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