Remove metadata from PDF files, using pdftk, exiftool and qpdf

clean_pdf.sh

# Ensure that required tools are installed and available in $PATH
command -v pdftk >/dev/null 2>&1 || { echo >&2 "pdftk is required but was not found.  Aborting."; exit 1; }
command -v exiftool >/dev/null 2>&1 || { echo >&2 "exiftool is required but was not found.  Aborting."; exit 1; }
command -v qpdf >/dev/null 2>&1 || { echo >&2 "qpdf is required but was not found.  Aborting."; exit 1; }

# Ensure that 1 cmdline argument was passed
if [ "$#" -ne 1 ]
then
  echo "Usage: cleanpdf.sh path-to-pdf-file.pdf"
  echo ""
  exit 1
fi
ifile="$1"

# Check if the file exists
if ! [[ -s "$ifile" ]]
then
   echo "$ifile either does not exist or is empty"
   exit 1
fi

# Name output file based on the input file
tmp=$(basename "$ifile" .pdf)
ofile="${tmp}_nometa.pdf"


# Remove metadata
echo "Processing $ifile ..."
echo ""
pdftk $ifile cat 1-end output /tmp/tmp1.pdf
exiftool -all:all= -overwrite_original /tmp/tmp1.pdf
qpdf --linearize /tmp/tmp1.pdf "$ofile"

# Change the access/modification date in the local Filesystem to a random date
randd=`date -d "$((RANDOM%12+2010))-$((RANDOM%12+1))-$((RANDOM%28+1)) $((RANDOM%23+1)):$((RANDOM%59+1)):$((RANDOM%59+1))" '+%Y%m%d%H%M.%S'`
# Note that the following command will zero the nanoseconds, an indication that the date has been tampered
touch -t "$randd" "$ofile"


echo ""
echo "Finished processing"
echo "Clean file written at $ofile"
echo ""
echo "New Meta:"

pdfinfo "$ofile"