PROLOG

       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.

NAME

       unlockpt — unlock a pseudo-terminal master/slave pair

SYNOPSIS

       #include <stdlib.h>

       int unlockpt(int fildes);

DESCRIPTION

       The  unlockpt() function shall unlock the slave pseudo-terminal device associated with the
       master to which fildes refers.

       Conforming applications shall ensure that they call unlockpt() before  opening  the  slave
       side of a pseudo-terminal device.

RETURN VALUE

       Upon  successful  completion, unlockpt() shall return 0. Otherwise, it shall return -1 and
       set errno to indicate the error.

ERRORS

       The unlockpt() function may fail if:

       EBADF  The fildes argument is not a file descriptor open for writing.

       EINVAL The fildes argument is not associated with a master pseudo-terminal device.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       None.

RATIONALE

       See the RATIONALE section for posix_openpt().

FUTURE DIRECTIONS

       None.

SEE ALSO

       grantpt(), open(), posix_openpt(), ptsname()

       The Base Definitions volume of POSIX.1‐2017, <stdlib.h>

COPYRIGHT

       Portions of this text are reprinted and  reproduced  in  electronic  form  from  IEEE  Std
       1003.1-2017,  Standard  for  Information Technology -- Portable Operating System Interface
       (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C)  2018  by
       the  Institute  of  Electrical  and Electronics Engineers, Inc and The Open Group.  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 http://www.opengroup.org/unix/online.html .

       Any typographical or formatting errors that appear in this page are most  likely  to  have
       been  introduced  during  the conversion of the source files to man page format. To report
       such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .