man3/unlockpt.3

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   2 .\" This page is in the public domain. - aeb
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   5 .TH UNLOCKPT 3 2017-07-13 "" "Linux Programmer's Manual"
   6 .SH NAME
   7 unlockpt \- unlock a pseudoterminal master/slave pair
   8 .SH SYNOPSIS
   9 .B #define _XOPEN_SOURCE
  10 .br
  11 .B #include <stdlib.h>
  12 .PP
  13 .BI "int unlockpt(int " fd ");"
  14 .PP
  15 .in -4n
  16 Feature Test Macro Requirements for glibc (see
  17 .BR feature_test_macros (7)):
  18 .in
  19 .PP
  20 .ad l
  21 .BR unlockpt ():
  22 .br
  23 .RS 4
  24 Since glibc 2.24:
  25     _XOPEN_SOURCE\ >=\ 500 ||
  26         (_XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED)
  27 .br
  28 Glibc 2.23 and earlier:
  29     _XOPEN_SOURCE
  30 .RE
  31 .ad
  32 .SH DESCRIPTION
  33 The
  34 .BR unlockpt ()
  35 function unlocks the slave pseudoterminal device
  36 corresponding to the master pseudoterminal referred to by
  37 .IR fd .
  38 .PP
  39 .BR unlockpt ()
  40 should be called before opening the slave side of a pseudoterminal.
  41 .SH RETURN VALUE
  42 When successful,
  43 .BR unlockpt ()
  44 returns 0.
  45 Otherwise, it returns \-1 and sets
  46 .I errno
  47 appropriately.
  48 .SH ERRORS
  49 .TP
  50 .B EBADF
  51 The
  52 .I fd
  53 argument is not a file descriptor open for writing.
  54 .TP
  55 .B EINVAL
  56 The
  57 .I fd
  58 argument is not associated with a master pseudoterminal.
  59 .SH VERSIONS
  60 .BR unlockpt ()
  61 is provided in glibc since version 2.1.
  62 .SH ATTRIBUTES
  63 For an explanation of the terms used in this section, see
  64 .BR attributes (7).
  65 .TS
  66 allbox;
  67 lb lb lb
  68 l l l.
  69 Interface       Attribute       Value
  70 T{
  71 .BR unlockpt ()
  72 T}      Thread safety   MT-Safe
  73 .TE
  74 .SH CONFORMING TO
  75 POSIX.1-2001, POSIX.1-2008.
  76 .SH SEE ALSO
  77 .BR grantpt (3),
  78 .BR posix_openpt (3),
  79 .BR ptsname (3),
  80 .BR pts (4),
  81 .BR pty (7)