[R] listing all files in a directory ending in ".xxx" in a script

[J C Nash]

When in a console (I was in Rstudio) I can run

dir("../provenance-of-rootfinding/", pattern="\\.Rmd")

to list all Rmd files in the specified directory.

However, when I try to run this in a script under

   Rscript --vanilla

I don't get the files to list.

Am I missing something obvious that I should know about?

JN