Perl SIGIO example

#!/bin/env perl

# http://stackoverflow.com/q/12640993/132382
#
# XXX - !!Error checking removed!!
#
# This produces:
#  -- SIGIO --
#  -- SIGIO --
#  -- SIGIO --
#  done

use strict; use warnings;
use Fcntl;
use v5.16;

$SIG{IO}= sub { say "-- SIGIO --" };

my ($fh);

if (! open($fh, '-|')) { # XXX Error checking
  # Child
  for ('one', 'two') {
    sleep 2;
    say;
  }
  exit;
}

# Parent
fcntl($fh, F_SETFL, fcntl($fh, F_GETFL, 0) | O_ASYNC); # XXX Error checking
fcntl($fh, F_SETOWN, 0 + $$);

# Wait a bit
while (time < ($^T + 10)) {
  sleep 1;
}

say "done";