How to crete R Mark Down files in R studio

need to install:
install.package("rmarkdown")

how to render Rmd file through terminal command line after $ssh username

$ echo "rmarkdown::render('sample.Rmd', clean=TRUE)" | R --slave

$ Rscript -e "rmarkdown::render('sample.Rmd', clean=TRUE)”

Need to have "pandoc" package on X11 or Linux machines.
$pandoc -v