¬ just serendipity 🍀 (not just serendipity)

Previously.

Problem statement: Given a password-protected .pdf file, remove its password. It’s indifferent whether the file gets overwritten or whether a new one is created.

ghostscript can do it:

gs -q -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sOutputFile=output.pdf -c .setpdfwrite -f input.pdf

qpdf can do it:

qpdf --decrypt --password="{my pass}" input.pdf output.pdf

I am not expected to memorize these CLI flags.

I do not want to look them up every time either.

There are various approaches to tackle this:

• a shell alias (alias foo=)
• a shell function foo() {}
• a shell script (*.sh)
• a comma script
• a copyable snippet (e.g. stored in Obsidian / LogSeq or some other digital garden / personal wiki / second brain app)
• a snippet (e.g. in RayCast or Espanso)
• ask the AI each time
• google search for it each time

Lately I’ve been favouring the shell script approach, so here we go with pdf_password_remove.sh:

Usage #

Remove password protection from PDF files.

# Interactive password prompt (most secure)
pdf_password_remove secret.pdf

# Process multiple files
pdf_password_remove report.pdf invoice.pdf contract.pdf

# Provide password via command line
pdf_password_remove --password=BANANA42SPLIT secret.pdf

# Custom output filename (single file only)
pdf_password_remove -o unlocked.pdf secret.pdf

Example Output #

% pdf_password_remove --password=PIZZA69SLICE financial-report.pdf tax-form.pdf
✓ Successfully processed: financial-report.pdf → financial-report-unlocked.pdf
✓ Successfully processed: tax-form.pdf → tax-form-unlocked.pdf

Summary: Successfully processed 2/2 file(s)

Features #

• Process single or multiple PDF files in one command
• Secure interactive password prompt (hidden input)
• Command-line password option for automation/scripts
• Default output naming: adds -unlocked suffix
• Custom output filename with -o flag (single file only)
• Clear success/failure indicators for each file
• Validates PDF files before processing

Prerequisites #

Requires either ghostscript (preferred) or qpdf to be installed:

# macOS
brew install ghostscript       # Preferred
brew install qpdf              # Alternative

# Linux
sudo apt install ghostscript   # Preferred - Debian/Ubuntu
sudo apt install qpdf          # Alternative

sudo dnf install ghostscript   # Preferred - Fedora
sudo dnf install qpdf          # Alternative

sudo pacman -S ghostscript     # Preferred - Arch
sudo pacman -S qpdf            # Alternative

The script automatically detects and uses whichever tool is available, preferring ghostscript if both are installed.

Security Note #

Using --password on the command line will expose the password in shell history and process lists. For sensitive documents, use the interactive prompt instead (default behavior when password is not provided).