unlockpt man page

unlockpt — unlock a pseudoterminal master/slave pair

Synopsis

#define _XOPEN_SOURCE
#include <stdlib.h>

int unlockpt(int fd);

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

unlockpt():

Since glibc 2.24:
   _XOPEN_SOURCE >= 500 ||
       (_XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED)
Glibc 2.23 and earlier:
   _XOPEN_SOURCE

Description

The unlockpt() function unlocks the slave pseudoterminal device corresponding to the master pseudoterminal referred to by fd.

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

Return Value

When successful, unlockpt() returns 0. Otherwise, it returns -1 and sets errno appropriately.

Errors

EBADF

The fd argument is not a file descriptor open for writing.

EINVAL

The fd argument is not associated with a master pseudoterminal.

Versions

unlockpt() 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
unlockpt() Thread safety MT-Safe

Conforming to

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

See Also

grantpt(3), posix_openpt(3), ptsname(3), pts(4), pty(7)

Colophon

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Referenced By

getpt(3), grantpt(3), ioctl_tty(2), posix_openpt(3), pts(4), ptsname(3), pty(7).

2017-07-13 Linux Programmer's Manual