man3/grantpt.3

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   2 .\" This page is in the public domain. - aeb
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   4 .TH GRANTPT 3 "2003-01-30" "PTY Control" "Linux Programmer's Manual"
   5 .SH NAME
   6 grantpt \- grant access to the slave pseudo-terminal
   7 .SH SYNOPSIS
   8 .nf
   9 .B #define _XOPEN_SOURCE
  10 .br
  11 .B #include <stdlib.h>
  12 .sp
  13 .BI "int grantpt(int " fd ");"
  14 .fi
  15 .SH DESCRIPTION
  16 The
  17 .BR grantpt ()
  18 function changes the mode and owner of the slave pseudo-terminal device
  19 (pty) corresponding to the master pty referred to by
  20 .IR fd .
  21 The user ID of the slave is set to the real UID of the calling process.
  22 The group ID is set to an unspecified value (e.g. tty).
  23 The mode of the slave is set to 0620 (crw\-\-w\-\-\-\-).
  24 .PP
  25 The behavior of
  26 .BR grantpt ()
  27 is unspecified if a signal handler is installed to catch SIGCHLD signals.
  28 .SH "RETURN VALUE"
  29 When successful,
  30 .BR grantpt ()
  31 returns 0. Otherwise, it returns \-1 and sets
  32 .I errno
  33 appropriately.
  34 .SH ERRORS
  35 .TP
  36 .B EACCES
  37 The corresponding slave pty could not be accessed.
  38 .TP
  39 .B EBADF
  40 The
  41 .I fd
  42 argument is not a valid open file descriptor.
  43 .TP
  44 .B EINVAL
  45 The
  46 .I fd
  47 argument is valid but not associated with a master pty.
  48 .SH "CONFORMING TO"
  49 POSIX 1003.1-2001
  50 .SH NOTES
  51 This is part of the Unix98 pty support, see
  52 .BR pts (4).
  53 Many systems implement this function via a setuid helper binary
  54 called "pt_chown". With Linux devpts no such helper binary is required.
  55 .SH "SEE ALSO"
  56 .BR open (2),
  57 .BR posix_openpt (3),
  58 .BR ptsname (3),
  59 .BR unlockpt (3),
  60 .BR pts (4)