To answer your other question about getting the child status, you shouldn't have to install a CHLD signal handler to do that. Perl will keep track of the child's exit status when you fork and create a pipe using open and will set $? when you close the pipe.

In fact, if you install a signal handler for SIGCHLD, perl won't keep track of the exit status for you, so I would use such a signal handler only if there are other compelling reasons to do so. In that case you'll have to do something like this:

our $pid; # remember the child's pid
our $status;
sub handle_sigchld {
  my $wpid = waitpid -1, WNOHANG; # use POSIX for WNOHANG
  if ($wpid == $pid) {
    $status = $?;
  }
}
...
$pid = open(INPIPE, "...|");
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