my $nfound = select($rout = $rin, $wout = $win, undef, undef);
# Check $nfound for errors.
if(vec($rout, fileno SIGRD, 1)) {
  my $byte;
  while(sysread(SIGRD, $byte, 1)) {
  if($term) {
    # INT/TERM arrived, kill sshs, modify some data, ...
    $term = 0;
  }
  else {
    # CHLD arrived, do waitpid(), modify some data, ...
  }
}