[Expectperl-discuss] IO::Pty not fooling isatty

[Andrea M. <and...@au...>]

When I use this script:


#!/usr/bin/perl -w
use strict;

use IPC::Open2;

use IO::Pty;

my $pid;
my $out;
my $in;

$in = new IO::Pty;

$out  = $in->slave;

$pid = open2 ($out, $in, './a.out');

while (<$out>)
{
    print $_;
}


with this C program (compiled to a.out):


#include <stdio.h>
#include <unistd.h>

int
main ()
{
  printf ("isatty 0 = %d, 1 = %d, 2 = %d\n", isatty (0),  isatty (1), isatty (2));
}


I get:

isatty 0 = 0, 1 = 0, 2 = 1


That means that the pseudo-terminal doesn't convince the isatty function
from glibc that it is a terminal (except for stderr that open2 does not
redirect).  That has unpleasant consequences, such as my C programs
using block buffering instead of line buffering when piped to that Perl
script - avoiding that is the only reason I tried IO::Pty.

Am I doing something wrong?



Andrea Monaco