#!/usr/bin/perl

use POSIX;
use String::ShellQuote qw(shell_quote);

unless (defined $ENV{CTC_HOME}) {
  $ENV{DONT_LOOP_FOREVER}++ or die "infinite loop detected";
  exec "source ~/.bash_profile && ".shell_quote($^X, $0, @ARGV);
  POSIX::_exit(255);
}

chdir($ENV{CTC_HOME});
...
[download]

Though, I have to admit I prefer the simpler shell wrapper solution given by Corion.