#/bin/bash

# First we remove the pdfmarks file, since we'll be building it from scratch
rm pdfmarks

# ChapterNumber is simple the number of the chapter, one chapter per pdf
ChapterNumber=0
NumberOfPages=1

# This loops over all the pdf files in the current directory
for f in $(ls *.pdf)
do
    # We add one to the chapter number
    ChapterNumber=$(($ChapterNumber+1))
    # And we print this weird line into our pdfmarks file
    echo "[/Title (Chapter $ChapterNumber) /Page $NumberOfPages /OUT pdfmark" >> pdfmarks

    # We get the number of pages from a small utility called pdfinfo, check if it's installed
    # We add the number of pages in the current file to the NumberOfPages counter
    NumberOfPages=$(($NumberOfPages + $(pdfinfo $f | grep -i "Pages:" | awk '{print $2}') ))

    # now we're finished with this file.. on to the next
done

gs -dBATCH -dNOPAUSE -sPAPERSIZE=a4 -sDEVICE=pdfwrite -sOutputFile="MASTER.pdf" $(ls *.pdf) pdfmarks