Need the filename of the Rnw when knitr runs in rStudio

Question

When working on a reproducible research project, I would like to know the name of the Rnw file that is being run to use as an R variable.

This would be analogous to

Answer 1

knitr now has a method for this: current_input()

https://github.com/yihui/knitr/issues/701