PDF Documents

Posted on 3 2026

The source material this series draws on covers installing Adobe Reader 11 via Wine under a 32-bit Windows XP emulation layer. That approach has not been relevant since Adobe dropped Linux support in 2013 and stopped updating the Windows version meaningfully around the same time. Kubuntu’s native PDF toolchain handles everything Acrobat Reader did and quite a lot it never did.

Okular

Okular is the KDE document viewer and the default PDF reader on Kubuntu. It handles PDF, EPUB, DjVu, PostScript, and a range of other document formats in a single application.

sudo apt install okular

For most day-to-day PDF reading, Okular is all that is needed. It renders faithfully, supports annotations, has a presentation mode, and integrates cleanly with the KDE desktop.

Okular can fill PDF forms and save the filled version. For signing PDFs with a digital signature it supports X.509 certificates, connecting to the certificate infrastructure built in the certificates and XCA sections of this series.

PDF form signing with Okular

To sign a PDF with your certificate:

  1. Open the PDF in Okular
  2. Go to Tools > Sign Document
  3. Select your signing certificate (the personal client certificate from the certificates section)
  4. Draw the signature field on the document
  5. Save the signed PDF

The signature uses the certificate from your local certificate store, including certificates loaded on the Yubikey PIV slot. When signing with a Yubikey, Okular will prompt for the PIV PIN and a touch.

LibreOffice Draw for PDF editing

For editing PDF content rather than just reading it, LibreOffice Draw opens PDF files and allows structural editing:

sudo apt install libreoffice-draw

Open a PDF via File > Open in LibreOffice Draw. Text, images, and shapes can be edited and the result exported back to PDF. The fidelity of editing depends on how the PDF was created: PDFs with embedded fonts and complex layout edit less cleanly than simpler documents.

Command line PDF tools

The poppler-utils package provides a set of command line tools for PDF manipulation:

sudo apt install poppler-utils

Useful commands:

# Extract text from a PDF
pdftotext document.pdf document.txt

# Extract specific pages as images
pdftoppm -r 300 -png document.pdf output-prefix

# Get PDF metadata
pdfinfo document.pdf

# Verify PDF structure
pdfinfo -meta document.pdf

The pdftk tool handles merging, splitting, and rotating PDFs:

sudo apt install pdftk-java

# Merge two PDFs
pdftk file1.pdf file2.pdf cat output merged.pdf

# Extract pages 3 to 7
pdftk input.pdf cat 3-7 output extracted.pdf

# Rotate all pages 90 degrees clockwise
pdftk input.pdf rotate 1-endeast output rotated.pdf

Brave PDF viewer

Brave’s built-in PDF viewer handles most PDF reading needs within the browser, including form filling. For PDFs downloaded from the web, opening them directly in Brave is often the most convenient approach without needing to save and open in a separate application.

When Acrobat is genuinely required

There are a small number of situations where a specific Acrobat feature has no native Linux equivalent:

Certified PDFs with Acrobat-specific features: Some enterprise workflows use PDF certifications or extended features that are Acrobat-specific. These are increasingly rare.

Adobe Sign: Adobe’s cloud signing service. If a workflow specifically requires Adobe Sign rather than a generic PDF signature, there is no Linux equivalent other than using the web interface in Brave.

Specific interactive form features: Some PDF forms use JavaScript that only Acrobat evaluates correctly. For these, the most pragmatic solution is using Brave’s PDF viewer, which uses the same underlying PDF engine as Chrome and handles most such forms.

If you genuinely need Acrobat for a specific form or workflow, the web version at https://acrobat.adobe.com/ handles most operations without installing any software. This is considerably cleaner than the Wine-based installation in the source material.

PDF as a format has been open and standardised under ISO 32000 since 2008. The notion that Acrobat is required to use PDFs on Linux was outdated a decade ago. Okular, LibreOffice, Brave, and the poppler utilities collectively cover everything a typical desktop user needs.