Save single page from PDF file as PNG image file

In the open source world, the best choice for PDF command line foo (and PDF foo in general) is almost always ghostscript. This is a quick way to extract a single page from a PDF file and save it as PNG file with a given (resolution in dpi):

#!/bin/bash
INFILE="$1"
OUTFILE="$2"
PAGE="$3"
RES="$4"
 
gs -dBATCH -dNOPAUSE -sDEVICE=png16m \
    -r$RES \
    -dFirstPage=$PAGE \
    -dLastPage=$PAGE \
    "-sOutputFile=$OUTFILE" \
    "$INFILE"

Example usage:

./pdf_page_to_png.sh input.pdf output_p3.png 3 200