pdftk-server — GitHub Copilot skill: install and PDF tasks

---
name: pdftk-server
description: 'Skill for using the command-line tool pdftk (PDFtk Server) for working with PDF files. Use when asked to merge PDFs, split PDFs, rotate pages, encrypt or decrypt PDFs, fill PDF forms, apply watermarks, stamp overlays, extract metadata, burst documents into pages, repair corrupted PDFs, attach or extract files, or perform any PDF manipulation from the command line.'
---

# PDFtk Server

PDFtk Server is a command-line tool for working with PDF documents. It can merge, split, rotate, encrypt, decrypt, watermark, stamp, fill forms, extract metadata, and manipulate PDFs in a variety of ways.

## When to Use This Skill

- Merging or joining multiple PDF files into one
- Splitting or bursting a PDF into individual pages
- Rotating PDF pages
- Encrypting or decrypting PDF files
- Filling PDF form fields from FDF/XFDF data
- Applying background watermarks or foreground stamps
- Extracting PDF metadata, bookmarks, or form field information
- Repairing corrupted PDF files
- Attaching or extracting files embedded in PDFs
- Removing specific pages from a PDF
- Collating separately scanned even/odd pages
- Compressing or decompressing PDF page streams

## Prerequisites

- PDFtk Server must be installed on the system
  - **Windows**: `winget install --id PDFLabs.PDFtk.Server`
  - **macOS**: `brew install pdftk-java`
  - **Linux (Debian/Ubuntu)**: `sudo apt-get install pdftk`
  - **Linux (Red Hat/Fedora)**: `sudo dnf install pdftk`
- Access to a terminal or command prompt
- Verify installation by running `pdftk --version`

## Step-by-Step Workflows

### Merge Multiple PDFs

```bash
pdftk file1.pdf file2.pdf cat output merged.pdf
```

Using handles for more control:

```bash
pdftk A=file1.pdf B=file2.pdf cat A B output merged.pdf
```

### Split a PDF into Individual Pages

```bash
pdftk input.pdf burst
```

### Extract Specific Pages

Extract pages 1-5 and 10-15:

```bash
pdftk input.pdf cat 1-5 10-15 output extracted.pdf
```

### Remove Specific Pages

Remove page 13:

```bash
pdftk input.pdf cat 1-12 14-end output output.pdf
```

### Rotate Pages

Rotate all pages 90 degrees clockwise:

```bash
pdftk input.pdf cat 1-endeast output rotated.pdf
```

### Encrypt a PDF

Set an owner password and a user password with 128-bit encryption (default):

```bash
pdftk input.pdf output secured.pdf owner_pw mypassword user_pw userpass
```

### Decrypt a PDF

Remove encryption using the known password:

```bash
pdftk secured.pdf input_pw mypassword output unsecured.pdf
```

### Fill a PDF Form

Populate form fields from an FDF file and flatten to prevent further edits:

```bash
pdftk form.pdf fill_form data.fdf output filled.pdf flatten
```

### Apply a Background Watermark

Place a single-page PDF behind every page of the input (input should have transparency):

```bash
pdftk input.pdf background watermark.pdf output watermarked.pdf
```

### Stamp an Overlay

Place a single-page PDF on top of every page of the input:

```bash
pdftk input.pdf stamp overlay.pdf output stamped.pdf
```

### Extract Metadata

Export bookmarks, page metrics, and document information:

```bash
pdftk input.pdf dump_data output metadata.txt
```

### Repair a Corrupted PDF

Pass a broken PDF through pdftk to attempt automatic repair:

```bash
pdftk broken.pdf output fixed.pdf
```

### Collate Scanned Pages

Interleave separately scanned even and odd pages:

```bash
pdftk A=even.pdf B=odd.pdf shuffle A B output collated.pdf
```

## Troubleshooting

| Issue | Solution |
|-------|----------|
| `pdftk` command not found | Verify installation; check that pdftk is in your system PATH |
| Cannot decrypt PDF | Ensure you are providing the correct owner or user password via `input_pw` |
| Output file is empty or corrupt | Check input file integrity; try running `pdftk input.pdf output repaired.pdf` first |
| Form fields not visible after fill | Use the `flatten` flag to merge fields into the page content |
| Watermark not appearing | Ensure the input PDF has transparent regions; use `stamp` for opaque overlays |
| Permission denied errors | Check file permissions on input and output paths |

## References

Bundled reference documents in the `references/` folder:

- [pdftk-man-page.md](references/pdftk-man-page.md) - Complete manual reference with all operations, options, and syntax
- [pdftk-cli-examples.md](references/pdftk-cli-examples.md) - Practical command-line examples for common tasks
- [download.md](references/download.md) - Installation and download instructions for all platforms
- [pdftk-server-license.md](references/pdftk-server-license.md) - PDFtk Server licensing information
- [third-party-materials.md](references/third-party-materials.md) - Third-party library licenses