Unlock and edit a PDF with a text editor

anti_watermark_pdf.sh

INPUT_FILE=$1
# Check if target file is set
if [ -z "$2" ]
    then
    # Ask confirmation before overwriting the existing file
    read -p "Overwrite the existing ${INPUT_FILE} (y/N)? "
    if [[ $REPLY =~ ^[Yy]$ ]]
        then
        TARGET_FILE=$INPUT_FILE
    else
        echo "Abort."
        exit 1
    fi
else
    TARGET_FILE="$2"
fi

# Temporary folder to use
TMP_DIR=./.tmp
mkdir -p $TMP_DIR

# Decrypt the PDF using ghostscript
UNENCRYPTED_PDF=$TMP_DIR/unencrypted.pdf
gs -q -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sOutputFile="${UNENCRYPTED_PDF}" -f "${INPUT_FILE}"

echo "PDF decrypted !"

# Uncompress the PDF with pdftk
UNCOMPRESSED_PDF=$TMP_DIR/uncompressed.pdf
pdftk "${UNENCRYPTED_PDF}" output "${UNCOMPRESSED_PDF}" uncompress
echo "PDF uncompressed".

# Edit the file
$EDITOR $UNCOMPRESSED_PDF

COMPRESSED_PDF=$TMP_DIR/compressed.pdf
# Compress the PDF file
pdftk "${UNCOMPRESSED_PDF}" output "${COMPRESSED_PDF}" compress
echo "New PDF compressed."

# Clean up obsolete temp files
rm "${UNENCRYPTED_PDF}"
rm "${UNCOMPRESSED_PDF}"
# Move new file to target
mv "${COMPRESSED_PDF}" "${TARGET_FILE}"
# Clean up temp folder
rmdir "${TMP_DIR}"

echo "Done. Saved in ${TARGET_FILE}."
exit 0