#!/bin/sh
set WRITEWHAT="bash vars"
# If you want to include your bash var's
# Escape the $'s that are not bash vars.
perl -le "$(cat <<MYPL
my $STDERRdata="", $STDOUTdata="";
while (\$i=<STDIN>){ chomp \$i;
 \$STDOUTdata .= "To stdout\n";
 \$STDERRdata .= "Write $WRITEWHAT from within the heredoc\n";
MYPL
print \$STDOUTdata; # Doing the pipe write at the end will save you
warn \$STDERRdata;  # a lot of frustration.
)" <myInputFile 1>prints.txt 2>warns.txt