man3/grantpt.3

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   4 .TH GRANTPT 3 2003-01-30 "GNU" "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.
  32 Otherwise, it returns \-1 and sets
  33 .I errno
  34 appropriately.
  35 .SH ERRORS
  36 .TP
  37 .B EACCES
  38 The corresponding slave pty could not be accessed.
  39 .TP
  40 .B EBADF
  41 The
  42 .I fd
  43 argument is not a valid open file descriptor.
  44 .TP
  45 .B EINVAL
  46 The
  47 .I fd
  48 argument is valid but not associated with a master pty.
  49 .SH "CONFORMING TO"
  50 POSIX.1-2001
  51 .SH NOTES
  52 This is part of the Unix98 pty support, see
  53 .BR pts (4).
  54 Many systems implement this function via a set-user-ID helper binary
  55 called "pt_chown". With Linux devpts no such helper binary is required.
  56 .SH "SEE ALSO"
  57 .BR open (2),
  58 .BR posix_openpt (3),
  59 .BR ptsname (3),
  60 .BR unlockpt (3),
  61 .BR pts (4),
  62 .BR feature_test_macros (7),
  63 .BR pty (7)