open EXT,"|extprog";
while (<>){
  @data = conv_data($_);
  print EXT "$data[0] $data[1]\n";
}
close EXT;

##</code><code>##

$run =
"mapproject -F --D_FORMAT=\%lf -I --ELLIPSOID=HELMERT1906  -Jt31/30/1:1 -R31/40/30/39 --MAP_SCALE_FACTOR=1.0000 ";
open FH, "<depths.asc.to" or die "could not open asc file\n";
if ( $pid = open RESULTS, "-|" ) {
    # I am the original process, so read from <RESULTS> below
}
else {
    # I am the kid
    if ( $pid1 = open STDIN, "-|" ) {
        # I am still the kid, but my STDIN is now piped from the grandkid
        exec "$run";
    }
    else {    # I am the grandkid: be a data pump
	while (<FH>) {	
	    print "$_\n";
	  }
        exit 0;
    }
}
while (<RESULTS>) {
    print $_;
}