What's --cwd for?

[anko]

Docs don't explain.

I was reviewing https://github.com/alanshaw/markdown-pdf/issues/120 and realised I don't know.

If I wanted to markdown-pdf in a different dir, I'd just cd to it like

( cd somewhere && markdown-pdf file.md )

Right? Why do we have --cwd? It seems the only place it's used to is as an option to phantomjs, but I don't know what that would do significantly differently with it either.