[galaxy-dev] Relative file path in Galaxy

Hi, My tool has a script reads a file in the same directory as the script. When I try to use relative path to read the file, it works by directly run it, but does not work when calling from Galaxy. Absolute path will work, but I want to know is there a way to do it using relative path. Can you give me some suggestion? myTool.pl use the following code the read the file in the same directory my $genusfiles = "genus.txt"; open (GENUSGP, "$genusfiles") or die "$genusfiles: $! \n"; close(GENUSGP); Thanks