r - qpdf.exe for compactPDF?

Question

I am trying to check a package that I have built (with vignette) using R CMD check --as-cran [my package] in my windows command prompt. All goes well until I get the message,

WARNING 'qpdf' is needed for checks on size reduction of PDFs

I have downloaded qpdf, put the unzipped folder in my program files directory, and added the bin folder to the PATH.

Not quite sure what else I need to do? I have the feeling I have not installed qpdf correctly or I need to build this program itself? I have read through the readme files and manual for qpdf which appear to be more aimed at unix users (which I have no experience with... I am your standard/regular windows user with little to no programming experience outside of statistical languages). I have had a go at trying to build qpdf using cgywin, but ended up failing to install zlib and prec. Any tips?

Answer 1

I would try

Sys.which(Sys.getenv("R_QPDF", "qpdf"))
Sys.getenv("PATH")

to establish that R is really not finding the qpdf executable, and see where it is looking. You probably shouldn't need to rebuild everything, just figure out why R is not finding the qpdf executable ... does running qpdf from a terminal window work ... ? How are you starting R, and did it have a chance to get the new PATH definition (i.e. do you need to open a new terminal window, or ?? reboot ??)

The incantation above was extracted from tools::compactPDF, from the default value of the qpdf argument, on a Linux machine. You should check for yourself, in case (e.g.) the Windows version is looking for qpdf.exe rather than qpdf ...