.\" %%%LICENSE_START(PUBLIC_DOMAIN)
.\" This page is in the public domain. - aeb
.\" %%%LICENSE_END
.\"
.TH GRANTPT 3 2015-08-08 "GNU" "Linux Programmer's Manual"
.SH NAME
grantpt \- grant access to the slave pseudoterminal
.SH SYNOPSIS
.nf
.BR "#define _XOPEN_SOURCE" "       /* See feature_test_macros(7) */"
.br
.B #include <stdlib.h>
.sp
.BI "int grantpt(int " fd ");"
.fi
.SH DESCRIPTION
The
.BR grantpt ()
function changes the mode and owner of the slave pseudoterminal device
corresponding to the master pseudoterminal referred to by
.IR 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.,
.IR tty ).
The mode of the slave is set to 0620 (crw\-\-w\-\-\-\-).
.PP
The behavior of
.BR grantpt ()
is unspecified if a signal handler is installed to catch
.B SIGCHLD
signals.
.SH RETURN VALUE
When successful,
.BR grantpt ()
returns 0.
Otherwise, it returns \-1 and sets
.I errno
appropriately.
.SH ERRORS
.TP
.B EACCES
The corresponding slave pseudoterminal could not be accessed.
.TP
.B EBADF
The
.I fd
argument is not a valid open file descriptor.
.TP
.B EINVAL
The
.I fd
argument is valid but not associated with a master pseudoterminal.
.SH VERSIONS
.BR grantpt ()
is provided in glibc since version 2.1.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.TS
allbox;
lb lb lb
l l l.
Interface	Attribute	Value
T{
.BR grantpt ()
T}	Thread safety	MT-Safe locale
.TE

.SH CONFORMING TO
POSIX.1-2001, POSIX.1-2008.
.SH NOTES
This is part of the UNIX 98 pseudoterminal support, see
.BR 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.
.SH SEE ALSO
.BR open (2),
.BR posix_openpt (3),
.BR ptsname (3),
.BR unlockpt (3),
.BR pts (4),
.BR pty (7)
.SH COLOPHON
This page is part of release 4.10 of the Linux
.I 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/.