#!/usr/bin/perl
use warnings;
use strict;
use Tk;

open(CHILD, "ls -laR h: |") or die "Can't open: $!";

my $mw = new MainWindow;
my $t = $mw->Scrolled("Text",-width => 80, -height => 25, -wrap => 'none');
$t->pack(-expand => 1);
CHILD->autoflush(1);
$mw->fileevent('CHILD', 'readable', [\&fill_text_widget, $mw]);
$mw->after(500);
MainLoop;

sub fill_text_widget {
    my ($widget) = @_;
    if (eof(CHILD)) {
        $widget->fileevent('CHILD', "readable", undef); # cancel binding
	return ;
    }
    if (sysread ('CHILD', $_, 4096)) {
        $t->insert('end', $_); # Append the data read
	$t->yview('end');
	$mw->bell;
    } else {
        # sysread returned undef. Problem with file
        $t->insert('end', "ERROR !!!"); 
        $widget->fileevent('CHILD', "readable", undef); # cancel binding
    }
}