Section: POSIX Programmer's Manual (3P)
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
--- unlock a pseudo-terminal master/slave pair
int unlockpt(int fildes);
function shall unlock the slave pseudo-terminal device associated with
the master to which
Conforming applications shall ensure that they call
before opening the slave side of a pseudo-terminal device.
Upon successful completion,
shall return 0. Otherwise, it shall return -1 and set
to indicate the error.
function may fail if:
argument is not a file descriptor open for writing.
argument is not associated with a master pseudo-terminal device.
The following sections are informative.
See the RATIONALE section for
The Base Definitions volume of POSIX.1-2008,
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
(This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
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