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  47 .TH UNLOCKPT 3C "Aug 14, 2002"
  48 .SH NAME
  49 unlockpt \- unlock a pseudo-terminal master/slave pair
  50 .SH SYNOPSIS
  51 .LP
  52 .nf
  53 #include <stdlib.h>
  54 
  55 \fBint\fR \fBunlockpt\fR(\fBint\fR \fIfildes\fR);
  56 .fi
  57 
  58 .SH DESCRIPTION
  59 .sp
  60 .LP
  61 The \fBunlockpt()\fR function unlocks the slave pseudo-terminal device
  62 associated with the master to which \fIfildes\fR refers.
  63 .sp
  64 .LP
  65 Portable applications must call \fBunlockpt()\fR before opening the slave side
  66 of a pseudo-terminal device.
  67 .SH RETURN VALUES
  68 .sp
  69 .LP
  70 Upon successful completion, \fBunlockpt()\fR returns \fB0\fR. Otherwise, it
  71 returns \fB\(mi1\fR and sets \fBerrno\fR to indicate the error.
  72 .SH ERRORS
  73 .sp
  74 .LP
  75 The \fBunlockpt()\fR function may fail if:
  76 .sp
  77 .ne 2
  78 .na
  79 \fB\fBEBADF\fR\fR
  80 .ad
  81 .RS 10n
  82 The \fIfildes\fR argument is not a file descriptor open for writing.
  83 .RE
  84 
  85 .sp
  86 .ne 2
  87 .na
  88 \fB\fBEINVAL\fR\fR
  89 .ad
  90 .RS 10n
  91 The \fIfildes\fR argument is not associated with a master pseudo-terminal
  92 device.
  93 .RE
  94 
  95 .SH ATTRIBUTES
  96 .sp
  97 .LP
  98 See \fBattributes\fR(5) for descriptions of the following attributes:
  99 .sp
 100 
 101 .sp
 102 .TS
 103 box;
 104 c | c
 105 l | l .
 106 ATTRIBUTE TYPE  ATTRIBUTE VALUE
 107 _
 108 Interface Stability     Standard
 109 _
 110 MT-Level        Safe
 111 .TE
 112 
 113 .SH SEE ALSO
 114 .sp
 115 .LP
 116 \fBopen\fR(2), \fBgrantpt\fR(3C), \fBptsname\fR(3C), \fBattributes\fR(5),
 117 \fBstandards\fR(5)
 118 .sp
 119 .LP
 120 \fISTREAMS Programming Guide\fR