If you want a cross platform way of dealing with paths, check out File::Spec. For instance, if you wanted to change the specific directory ./foobar to an absolute, non platform specific (*nix) directory you could use the following:

use strict;
use warnings;
use File::Spec;

# print a path that is system independent
print "The dir is ", File::Spec->rel2abs("./foobar"), "\n";
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You can do all sorts of cool things with File::Spec involving directories, allowing you to use Unix style names on Windoze and Visa versa. The only caveat is to use $ENV{HOME} for the home directory -- ~/ is only the home directory for some shells, so it is not properly translated.