This is how I like to do that kind of thing–

use strictures;
use Path::Class "file";
use File::Spec;

my $script = file( File::Spec->rel2abs(__FILE__) );

print $script, $/;

printf("HURR -> %s\nDERR -> %s\nDERP -> %s\n",
       $script->basename,
       $script->parent,
       $script->as_foreign("Win32"),
      );

__END__
/Users/moo/depot/tmp/pm-972505.pl
HURR -> pm-972505.pl
DERR -> /Users/moo/depot/tmp
DERP -> \Users\moo\depot\tmp\pm-972505.pl
[download]

You can chain ->parent and use the methods like relative to do lots of easy to follow path handling code; Path::Class::File, Path::Class::Dir. Sidenote: cd'ing around in scripts, to me, has a pretty strong code smell and whenever I see it in the wild it seems to come with too many assumptions and too little error checking.