Build all Rmd files under a directorySource:
List all Rmd files recursively under a directory, and compile them using
A directory path.
Whether to force building all Rmd files. By default, an Rmd file is built only if it is newer than its output file(s).
A regular expression to match output filenames that should be ignored when testing if the modification time of the Rmd source file is newer than its output files.