man3/getpt.3

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   7 .TH GETPT 3 2015-03-02 "GNU" "Linux Programmer's Manual"
   8 .SH NAME
   9 getpt \- open the pseudoterminal master (PTM)
  10 .SH SYNOPSIS
  11 .nf
  12 .BR "#define _GNU_SOURCE" "             /* See feature_test_macros(7) */"
  13 .B #include <stdlib.h>
  14 .PP
  15 .B "int getpt(void);"
  16 .fi
  17 .SH DESCRIPTION
  18 .BR getpt ()
  19 opens a pseudoterminal master and returns its file descriptor.
  20 It is equivalent to
  21 .PP
  22 .in +4n
  23 .EX
  24 open(/dev/ptmx, O_RDWR | O_NOCTTY);
  25 .EE
  26 .in
  27 .PP
  28 on Linux systems, though the pseudoterminal master is located
  29 elsewhere on some systems that use GNU Libc.
  30 .SH RETURN VALUE
  31 .BR getpt ()
  32 returns an open file descriptor upon successful completion.
  33 Otherwise, it
  34 returns \-1 and sets
  35 .I errno
  36 to indicate the error.
  37 .SH ERRORS
  38 .BR getpt ()
  39 can fail with various errors described in
  40 .BR open (2).
  41 .SH VERSIONS
  42 .BR getpt ()
  43 is provided in glibc since version 2.1.
  44 .SH ATTRIBUTES
  45 For an explanation of the terms used in this section, see
  46 .BR attributes (7).
  47 .TS
  48 allbox;
  49 lb lb lb
  50 l l l.
  51 Interface       Attribute       Value
  52 T{
  53 .BR getpt ()
  54 T}      Thread safety   MT-Safe
  55 .TE
  56 .SH CONFORMING TO
  57 .BR getpt ()
  58 is glibc-specific;
  59 use
  60 .BR posix_openpt (3)
  61 instead.
  62 .SH SEE ALSO
  63 .BR grantpt (3),
  64 .BR posix_openpt (3),
  65 .BR ptsname (3),
  66 .BR unlockpt (3),
  67 .BR ptmx (4),
  68 .BR pty (7)