man3/unlockpt.3

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