The other comments (regarding the difference between system and backticks) are entirely correct.

I have a separate comment, however -- if you want to identify the current working directory, you should use Perl's core module Cwd instead of invoking system tools. (try perldoc Cwd).

use Cwd;
print getcwd();
[download]

The biggest advantage is that using Cwd does not have portability issues -- your tool will continue to work correctly on whatever OS you need to use Perl on.

If you already know this, great. Just my $0.02 US.