Making PDFs editable
I automate everything and PDFs are so easy to fill in automatically. It’s a digital world and we just live in it.
It’s so frustrating to get a “protected form” that doesn’t allow for appending documents, automated form completion or even filling out fields. It’s silly because all of these forms are printable. Many years ago, I just created an official form from scratch myself because I couldn’t find it online. Without checking a signature, forms can’t be secure. For example, one could easily write a program that takes a picture and recreates the form. Remember, in the digital world something is either secure from math (crypto) or it isn’t. The security in the transaction is provided by authenticating the user’s email. Even better, let’s move past forms and use the authentication in a website or mobile app.
Let’s do the right thing and move past forms caught in the middle ground of insecure and not usable. I think folks lock forms to prevent changes to the document, don’t do that.
Below is the code to fix this. You will need to use linux or windows subsystem for linux. While I can’t think of an evil use case, use this responsibly. (My goal in doing this is always to fill in data into a form.)
Use a little bash to print with ghostscript. Protip: this isn’t “hacking”, this is just printing.
filename=$1
outfile="${filename%.*}_clean.pdf"
echo $outfile
gs -q -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sOutputFile=$outfile -c .setpdfwrite -f $1
tim
July 17, 2025 at 11:16 am
file=”myfile.pdf”; gs -q -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sOutputFile=”${file%.*}_clean.pdf” “$file”
tim
December 5, 2025 at 3:08 pm
#!/usr/bin/env zsh
# unlock-pdf — re-writes a PDF to strip protections (using Ghostscript)
set -euo pipefail
function usage() {
cat <<EOF
Usage: $(basename $0) input.pdf [output.pdf]
If output file is omitted, it writes to _clean.pdf
Examples:
$(basename $0) secret.pdf
$(basename $0) secret.pdf secret_unlocked.pdf
EOF
exit 1
}
if (( $# 2 )); then
usage
fi
local input=”$1″
if [[ ! -f “$input” ]]; then
echo “Error: input file ‘$input’ not found” >&2
exit 1
fi
local output
if (( $# == 2 )); then
output=”$2″
else
local base=”${input%.*}”
output=”${base}_clean.pdf”
fi
echo “Unlocking → $output”
# Ghostscript command
gs -q \
-dNOPAUSE -dBATCH -dSAFER \
-sDEVICE=pdfwrite \
-dCompatibilityLevel=1.5 \
-dPDFSETTINGS=/default \
-sOutputFile=”$output” \
“$input”
echo “Done: $output”%