v7 man page for unlockpt

UNLOCKPT(3)						     Linux Programmer's Manual						       UNLOCKPT(3)

NAME
       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
       This  page is part of release 4.15 of the Linux 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/.

								    2017-07-13							       UNLOCKPT(3)