man3/getpt.3

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   7 .TH GETPT 3 2021-03-22 "Linux man-pages (unreleased)"
   8 .SH NAME
   9 getpt \- open a new pseudoterminal master
  10 .SH LIBRARY
  11 Standard C library
  12 .RI ( libc ", " \-lc )
  13 .SH SYNOPSIS
  14 .nf
  15 .BR "#define _GNU_SOURCE" "             /* See feature_test_macros(7) */"
  16 .B #include <stdlib.h>
  17 .PP
  18 .B "int getpt(void);"
  19 .fi
  20 .SH DESCRIPTION
  21 .BR getpt ()
  22 opens a new pseudoterminal device and returns a file descriptor
  23 that refers to that device.
  24 It is equivalent to opening the pseudoterminal multiplexor device
  25 .PP
  26 .in +4n
  27 .EX
  28 open("/dev/ptmx", O_RDWR);
  29 .EE
  30 .in
  31 .PP
  32 on Linux systems, though the pseudoterminal multiplexor device is located
  33 elsewhere on some systems that use the GNU C library.
  34 .SH RETURN VALUE
  35 .BR getpt ()
  36 returns an open file descriptor upon successful completion.
  37 Otherwise, it
  38 returns \-1 and sets
  39 .I errno
  40 to indicate the error.
  41 .SH ERRORS
  42 .BR getpt ()
  43 can fail with various errors described in
  44 .BR open (2).
  45 .SH VERSIONS
  46 .BR getpt ()
  47 is provided in glibc since version 2.1.
  48 .SH ATTRIBUTES
  49 For an explanation of the terms used in this section, see
  50 .BR attributes (7).
  51 .ad l
  52 .nh
  53 .TS
  54 allbox;
  55 lbx lb lb
  56 l l l.
  57 Interface       Attribute       Value
  58 T{
  59 .BR getpt ()
  60 T}      Thread safety   MT-Safe
  61 .TE
  62 .hy
  63 .ad
  64 .sp 1
  65 .SH STANDARDS
  66 .BR getpt ()
  67 is glibc-specific;
  68 use
  69 .BR posix_openpt (3)
  70 instead.
  71 .SH SEE ALSO
  72 .BR grantpt (3),
  73 .BR posix_openpt (3),
  74 .BR ptsname (3),
  75 .BR unlockpt (3),
  76 .BR ptmx (4),
  77 .BR pty (7)