.\" %%%LICENSE_START(PUBLIC_DOMAIN)

.\" This page is in the public domain. - aeb

.\" %%%LICENSE_END

.\"

.TH UNLOCKPT 3 2017-07-13 "" "Linux Programmer's Manual"

.SH NAME

unlockpt \- unlock a pseudoterminal master/slave pair

.SH SYNOPSIS

.B #define _XOPEN_SOURCE

.br

.B #include <stdlib.h>

.PP

.BI "int unlockpt(int " fd ");"

.PP

.in -4n

Feature Test Macro Requirements for glibc (see

.BR feature_test_macros (7)):

.in

.PP

.ad l

.BR unlockpt ():

.br

.RS 4

Since glibc 2.24:

    _XOPEN_SOURCE\ >=\ 500 ||

        (_XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED)

.br

Glibc 2.23 and earlier:

    _XOPEN_SOURCE

.RE

.ad

.SH DESCRIPTION

The

.BR unlockpt ()

function unlocks the slave pseudoterminal device

corresponding to the master pseudoterminal referred to by

.IR fd .

.PP

.BR unlockpt ()

should be called before opening the slave side of a pseudoterminal.

.SH RETURN VALUE

When successful,

.BR unlockpt ()

returns 0.

Otherwise, it returns \-1 and sets

.I errno

appropriately.

.SH ERRORS

.TP

.B EBADF

The

.I fd

argument is not a file descriptor open for writing.

.TP

.B EINVAL

The

.I fd

argument is not associated with a master pseudoterminal.

.SH VERSIONS

.BR unlockpt ()

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 unlockpt ()

T}	Thread safety	MT-Safe

.TE

.SH CONFORMING TO

POSIX.1-2001, POSIX.1-2008.

.SH SEE ALSO

.BR grantpt (3),

.BR posix_openpt (3),

.BR ptsname (3),

.BR pts (4),

.BR pty (7)

.SH COLOPHON

This page is part of release 4.15 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/.