Stirling

Enabling PDF to CBR Conversion in Stirling PDF

Overview#

Stirling PDF can convert PDF files into the Comic Book RAR (.cbr) format. This process relies on an external command-line utility, rar, which is not included by default. To enable this feature, you must first install the rar utility on your system and then make it accessible to Stirling PDF.

What is a CBR file?#

A CBR (Comic Book RAR) file is an archive used for distributing digital comic books. It is essentially a collection of sequential image files (e.g., JPEG, PNG) compressed into a single file using RAR compression.

While CBR is a popular format, it requires the proprietary rar utility for creation. Its more common, open-standard alternative is CBZ (Comic Book ZIP), which is supported by Stirling PDF out of the box.

Step 1: Install the rar Command-Line Utility#

The rar executable must be available in the environment that runs Stirling PDF. A native installation needs a binary for the host OS; a Linux container needs a Linux binary matching its architecture and runtime libraries.

Linux#

The easiest method is to use your distribution's package manager.

Debian / Ubuntu: The rar package is available in the non-free repository.

bash
sudo apt update
sudo apt install rar

Fedora / CentOS / RHEL: The rar package is available in the RPM Fusion "non-free" repository.

bash
# First, enable the RPM Fusion non-free repository for your system.
# See https://rpmfusion.org/Configuration for instructions.

# Then, install rar
sudo dnf install rar  # For Fedora, RHEL 8+, CentOS Stream
# or
sudo yum install rar  # For CentOS 7

Manual Installation (Any Linux Distribution):

  1. Visit the official download page: rarlab.com/download.htm.
  2. Download the "RAR for Linux x64" command-line version.
  3. Extract the archive and install the binary:
    bash
    # The version number (e.g., 712, as of writing this guide) will change.
# Use the actual filename.
tar -xzf rarlinux-x64-*.tar.gz

# Move the binary to a standard location in your system's PATH
sudo mv rar/rar /usr/local/bin/

# Ensure it has execute permissions
sudo chmod +x /usr/local/bin/rar

Windows#

  1. Download the "WinRAR and RAR command line tools" from rarlab.com/download.htm.
  2. Extract the downloaded archive.
  3. Copy the rar.exe file to a folder that is included in your system's PATH environment variable. A common and reliable location is C:\Windows\System32.
  4. If Stirling PDF is already running, restart it to ensure it recognizes the updated PATH.

macOS#

The recommended method is to use the Homebrew package manager.

bash
brew install rar

Step 2: Configure Stirling PDF#

After obtaining the appropriate rar binary, follow the instructions for your runtime environment.

For Non-Docker Users#

If you installed Stirling PDF directly on your operating system (without Docker), no further configuration is needed. As long as the rar command is available in your system's PATH, Stirling PDF will automatically (after restart) detect and use it.

For Docker Users#

Provide a Linux rar binary compatible with the container architecture and its required libraries. The mount below is suitable only when the host path contains such a binary; installing it in a custom image is another option.

yaml
services:
  stirling-pdf:
    image: docker.stirlingpdf.com/stirlingtools/stirling-pdf:latest
    ports:
      - '8080:8080'
    volumes:
      - ./StirlingPDF/trainingData:/usr/share/tessdata
      - ./StirlingPDF/extraConfigs:/configs
      - ./StirlingPDF/customFiles:/customFiles/
      - ./StirlingPDF/logs:/logs/
      - ./StirlingPDF/pipeline:/pipeline/
      # Add the following line to mount the rar binary
      - /usr/local/bin/rar:/usr/local/bin/rar:ro

Windows Docker hosts: A Windows rar.exe cannot run inside the Linux Stirling PDF container. Supply a compatible Linux binary in the container; do not mount the Windows executable as /usr/local/bin/rar.

Step 3: Verification#

Confirm that Stirling PDF can access the rar command.

  • For Docker Users: Execute a command inside the running container.

    bash
    docker exec -it stirling-pdf rar

  • For Non-Docker Users: Check if the rar command is recognized in your terminal.

    bash
    # On Linux and macOS
which rar

# On Windows
where rar

In both cases, a successful setup will display the RAR version and usage information. An error like "command not found" means there is a problem with the installation or PATH.

Important Considerations#

License Note#

RAR is shareware with a 40-day evaluation period. Continued use requires a licence under the official RAR licence terms, including personal use.

Alternative: Use the CBZ Format#

For broader compatibility and to avoid proprietary software, using the CBZ (Comic Book ZIP) format is highly recommended.

  • CBZ uses the open and universal ZIP standard.
  • The PDF to CBZ tool is enabled in Stirling PDF by default and requires no extra software.
  • CBZ is supported by virtually all modern comic book reader applications.
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