NAME

       unlockpt - unlock a pseudoterminal master/slave pair

LIBRARY

       Standard C library (libc, -lc)

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
           glibc 2.23 and earlier:
               _XOPEN_SOURCE

DESCRIPTION

       The  unlockpt()  function  unlocks  the  slave  pseudoterminal device corresponding to the
       master pseudoterminal referred to by the file descriptor 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  to
       indicate the error.

ERRORS

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

       EINVAL The fd argument is not associated with a master pseudoterminal.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       ┌───────────────────────────────────────────────────────────────┬───────────────┬─────────┐
       │Interface                                                      │ Attribute     │ Value   │
       ├───────────────────────────────────────────────────────────────┼───────────────┼─────────┤
       │unlockpt()                                                     │ Thread safety │ MT-Safe │
       └───────────────────────────────────────────────────────────────┴───────────────┴─────────┘

STANDARDS

       POSIX.1-2008.

HISTORY

       glibc 2.1.  POSIX.1-2001.

SEE ALSO

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