pdftk A=src.pdf B=blank.pdf cat A1 B1 A2-end output res.pdf
Hope you like this script, just save it as
pdfInsertBlankPageAt.sh, add execute permissions, and run.
./pdfInsertBlankPageAt 5 src.pdf res.pdf
if [ $# -ne 3 ]
echo "Usage example: ./pdfInsertBlankPageAt 5 src.pdf res.pdf"
pdftk A=$2 B=blank.pdf cat A1-$(($1-1)) B1 A$1-end output $3
cat A1 B1 A2-end means that the output file will contain the first page of document A (
src.pdf) followed by the first page of document B (
blank.pdf) followed by the rest (pages 2 to end) of document B. This operation is called concatenation, Linux
cat is very often used to display text, but it is interesting when used with more than one argument.