#!/usr/local/bin/perl -w

use strict;

use POSIX ":sys_wait_h";

my $avail;

sub REAPER {
    my $child;
    while ($child = waitpid(-1,&WNOHANG()) > 0) {
        $avail += ! $?;  # 0 means success, non-zero means failure
    }
    $SIG{CHLD} = \&REAPER;
}

$SIG{CHLD} = \&REAPER;

for (0..2,0..2) {
    if (fork) {
    } else {
        exit $_;
    }
}

print "$avail\n";