Add a blank page to a pdf

add-blank-page-to-pdf.sh

#!/usr/bin/env bash

# Count pages in all pdf files in the current directory:
#
#   pagecount .
#
# Count pages in this pdf:
#
#   pagecount file.pdf
#
function pagecount() {
  # brew install exiftool
  command exiftool -T -filename -PageCount -s3 -ext pdf "$1" | cut -f2 -d$'\t'
}

# Add a blank page to an existing pdf
#
#   addblank file.pdf out.pdf
#
function addblank() {
  in="$1"
  out="$2"
  blank="blank.pdf"
  if [ ! -f "$blank" ]
  then
    # brew install imagemagick
    # Use ImageMagick to create a Letter-sized blank pdf
    command convert xc:none -page Letter "$blank"
  fi
  # Use the built-in macOS Python script to combine pdf filesj
  script="/System/Library/Automator/Combine PDF Pages.action/Contents/Resources/join.py"
  "$script" -o "$out" "$in" "$blank"
}

# Example usage:

for f in *ebook.pdf
do
  n=$(pagecount "$f")
  if [[ $((n%2)) -eq 1 ]]
  then
    echo "Add blank.pdf to $f"
    addblank "$f" "${f%.pdf}-even.pdf"
  else
    cp -f "$f" "${f%.pdf}-even.pdf"
  fi
done