Stat::lsMode generates mode and permission strings that look like
the ones generated by the Unix ls -l command.  For example, a
regular file that is readable by everyone and writable only by its
owner has the mode string -rw-r--r--.  Stat::lsMode will either
examine the file and produce the right mode string for you, or you
can pass it the mode that you get back from Perl's stat call.