The problem with $ENV{PWD} is that it doesn't stay "linked." i.e.

print $ENV{PWD},"\n";
chdir("..")
print $ENV{PWD},"\n";
[download]

will print the same thing twice, which is probably not what you want. (If you use Cwd and ask it to override chdir, it will automatically keep $ENV{PWD} in sync with the actual current working directory, but by default it is not kept in sync).

--JAS