Polling pipes does not seem to work correctly on Fedora 1.  Two perl
scripts follow that demonstrate the problem.

The below scripts work on all distros that I have tested, including 
RH9, but fails on Fedora 1.  I have not tried the test Fedora 2.

Ray

#!/usr/local/bin/perl -w
# This script is called "test.pl" and is run in the pipe.

use strict;
$| = 1;

print "out1\n";
sleep 3;
print "out2\n";
sleep 3;
print "out3\n";
sleep 3;
print "out4\n";
exit;

Following is a script that invokes the above script.

#!/usr/local/bin/perl -w
# This script polls a command pipe by checking the filesize
# of the pipe's file handle.
use Tk;
use strict;

my $MW = MainWindow->new;
my $txt = $MW->Text->pack;

open (MY_PIPE, "test.pl |") or die "Couldn't open: $!\n";
my $pipe = \*MY_PIPE;

$MW->repeat(50 => \&read_pipe);

MainLoop;

sub read_pipe {
   # Read from the pipe if data is present there.
   my $size = -s $pipe;
   if ($size) {
      my $line;
      sysread($pipe,$line,$size);
      return unless $line;
      $txt->insert('end', "$line");
      $MW->update;
   }
}