Get the number of pages in a PDF document

Question

This question is for referencing and comparing. The solution is the accepted answer below.

Many hours have I searched for a fast and easy, but mostly a

Answer 1

Here is a R function that reports the PDF file page number by using the pdfinfo command.

pdf.file.page.number <- function(fname) {
    a <- pipe(paste("pdfinfo", fname, "| grep Pages | cut -d: -f2"))
    page.number <- as.numeric(readLines(a))
    close(a)
    page.number
}
if (F) {
    pdf.file.page.number("a.pdf")
}