I would say current behavior seems right. There is a slight difference between printing nothing and matching nothing, and adding a return 0 unconditionally will make them indistinguishable.

EDIT: I'm being dumb here, just noticed string join " " is changing status, so my above statement is not true.

There is a slight difference between printing nothing and matching nothing, and adding a return 0 unconditionally will make them indistinguishable.

I don't understand, what's the difference here? I don't think "matching" applies here because we just print the dirstack entries one by one.

I think we should probably change string join here. Returning false on string join ' ' x is weird. Returning false on string join ' ' seems okay still, because in that case the output is empty.

dirs always prints at least one result, namely the current directory. So right now the return value is different depending on whether it prints only one (false) or more than one (true), which doesn't seem useful. It should just return true.

Yeah, makes sense. Merged!