#!/usr/bin/perl 
# consent.cgi
BEGIN { use CGI::Carp 'fatalsToBrowser'; }

use strict;
use warnings;
use CGI qw(:standard);
use Fcntl ':flock';
# ......

# as a curiosity also.. 
my $iam = `whoami`;

open(STDERR, '>>', '/home/myself/errlog') or die($!);
warn("I am [$iam]");