Program does nothing when run without arguments

[ctsrc]

When fddf is run without arguments, nothing observable happens. No output.

IMO it would be preferable to have it act in either of the following ways:

• Either, do like ls and use the current working directory when no argument is provided. This makes the most sense for fddf IMO since fddf does not modify any files so it is safe to run fddf somewhere by accident.

• Or, make the roots argument required (see https://docs.rs/clap/2.33.0/clap/struct.Arg.html#method.required and press the pluss sign on the side to expand the description) so that clap reports an error to the user when fddf is run without any arguments. Personally I think making the argument required would not be as great because it means more typing.

[birkenfeld]

Agreed, will implement this with option 1.