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

# datastream.pl - Print local time every three seconds.

$| = 1; # unbuffered STDOUT

while ( 1 ) {
    print scalar(localtime), "\n";
    sleep 3;
}

#!/usr/bin/perl

use warnings;
use strict;

# readstream.pl

use Fcntl;
fcntl(STDIN, F_SETFL, O_NONBLOCK);

my $input;
my $res;
my $str = "";
my $reading = 0;
my $notread = 0;
while(1) {
    $res = sysread(STDIN, $input, 1);
    if (defined($res)) {
        $reading = 1;
        $str .= $input;
        if ($notread) {
            print "Unsuccessful attempts to read: $notread.\n";
        }
        $notread = 0;
    } else {
        if ($reading == 1) {
            print $str;
        }
        $reading = 0;
        $notread++;
        $str = "";
    }
}

datastream.pl | readstream.pl