man3/posix_openpt.3

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  25 .TH POSIX_OPENPT 3 2010-10-04 "" "Linux Programmer's Manual"
  26 .SH NAME
  27 posix_openpt \- open a psuedoterminal device
  28 .SH SYNOPSIS
  29 .nf
  30 .B #include <stdlib.h>
  31 .B #include <fcntl.h>
  32 .sp
  33 .BI "int posix_openpt(int " flags ");"
  34 .fi
  35 .sp
  36 .in -4n
  37 Feature Test Macro Requirements for glibc (see
  38 .BR feature_test_macros (7)):
  39 .in
  40 .sp
  41 .ad l
  42 .BR posix_openpt ():
  43 _XOPEN_SOURCE\ >=\ 600
  44 .ad b
  45 .SH DESCRIPTION
  46 The
  47 .BR posix_openpt ()
  48 function opens an unused psuedoterminal master device, returning a
  49 file descriptor that can be used to refer to that device.
  50
  51 The
  52 .I flags
  53 argument is a bit mask that ORs together zero or more of
  54 the following flags:
  55 .TP
  56 .B O_RDWR
  57 Open the device for both reading and writing.
  58 It is usual to specify this flag.
  59 .TP
  60 .B O_NOCTTY
  61 Do not make this device the controlling terminal for the process.
  62 .SH "RETURN VALUE"
  63 On success,
  64 .BR posix_openpt ()
  65 returns a nonnegative file descriptor which is the lowest
  66 numbered unused descriptor.
  67 On failure, \-1 is returned, and
  68 .I errno
  69 is set to indicate the error.
  70 .SH ERRORS
  71 See
  72 .BR open (2).
  73 .SH VERSIONS
  74 Glibc support for
  75 .BR posix_openpt ()
  76 has been provided since version 2.2.1.
  77 .SH "CONFORMING TO"
  78 .BR posix_openpt ()
  79 is part of the UNIX 98 psuedoterminal support (see
  80 .BR pts (4)).
  81 This function is specified in POSIX.1-2001.
  82 .SH NOTES
  83 This function is a recent invention in POSIX.
  84 Some UNIX implementations that support System V
  85 (aka UNIX 98) psuedoterminals don't have this function, but it
  86 is easy to implement:
  87 .in +4n
  88 .nf
  89
  90 int
  91 posix_openpt(int flags)
  92 {
  93     return open("/dev/ptmx", flags);
  94 }
  95 .fi
  96 .in
  97 .SH "SEE ALSO"
  98 .BR open (2),
  99 .BR getpt (3),
 100 .BR grantpt (3),
 101 .BR ptsname (3),
 102 .BR unlockpt (3),
 103 .BR pts (4),
 104 .BR pty (7)