man3/unlockpt.3

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   4 .TH UNLOCKPT 3 "2003-01-30" "PTY Control" "Linux Programmer's Manual"
   5 .SH NAME
   6 unlockpt \- unlock a pseudo-terminal master/slave pair
   7 .SH SYNOPSIS
   8 .nf
   9 .B #define _XOPEN_SOURCE
  10 .br
  11 .B #include <stdlib.h>
  12 .sp
  13 .BI "int unlockpt(int " fd ");"
  14 .fi
  15 .SH DESCRIPTION
  16 The
  17 .IR unlockpt ()
  18 function unlocks the slave pseudo-terminal device
  19 (pty) corresponding to the master pty referred to by
  20 .IR fd .
  21 .PP
  22 .IR unlockpt ()
  23 should be called before opening the slave side of a pty.
  24 .SH "RETURN VALUE"
  25 When successful,
  26 .IR unlockpt ()
  27 returns 0. Otherwise, it returns \-1 and sets
  28 .I errno
  29 appropriately.
  30 .SH ERRORS
  31 .TP
  32 .B EBADF
  33 The
  34 .I fd
  35 argument is not a file descriptor open for writing.
  36 .TP
  37 .B EINVAL
  38 The
  39 .I fd
  40 argument is not associated with a master pty.
  41 .SH "CONFORMING TO"
  42 POSIX 1003.1-2001.
  43 .SH "SEE ALSO"
  44 .IR grantpt (3),
  45 .BR posix_openpt (3),
  46 .IR ptsname (3),
  47 .BR pts (4),
  48 .BR pty (7)