perl script.pl --help
    script.pl [-desv] [long options...] <some-arg>
        -d STR --directory STR  the working directory </Users/Desktop>
        -e STR --extension STR  the file extension <.txt/r>
        -s STR --separator STR  the separating character<"\t">
        --sql STR               the sql

        -v --verbose            print extra stuff
        --help                  print usage message and exit