I came up with a minimal example of the fork writing to it's own xterm. It's kindof weird, trying get the ppid and pid, but this worked on linux. (At least it shows the concept). A second delay is needed to get the pids to showup properly.

#!/usr/bin/perl
use warnings;
use strict;
use Proc::ProcessTable;

my $time = time();

 my $pid;
 my $pid1 = open(PH,"| xterm -T $time -e bash");

 print "pidinit $pid1\n";

 sleep 1;

 for my $p (@{new Proc::ProcessTable->table}){
         if($p->ppid == $pid1){
                $pid = $p->pid;
           }
 }

 print "$pid\n";
      
open(FH,">/proc/$pid/fd/1") or warn $!;
  for(1..1000){print STDOUT $_,"\n"; print FH $_.'a',"\n";sleep 1;}
close FH;
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