I found using R studio the easiest way, but if wanting to control from the command line, then a simple R script can do the trick using rmarkdown render command (as mentioned above). Full script details here
#!/usr/bin/env R
# Render R markdown to PDF.
# Invoke with:
# > R -q -f make.R --args my_report.Rmd
# load packages
require(rmarkdown)
# require a parameter naming file to render
if (length(args) == 0) {
stop("Error: missing file operand", call. = TRUE)
} else {
# read report to render from command line
for (rmd in commandArgs(trailingOnly = TRUE)) {
# render Rmd to PDF
if ( grepl("\\.Rmd$", rmd) && file.exists(rmd)) {
render(rmd, pdf_document())
} else {
print(paste("Ignoring: ", rmd))
}
}
}