Bookdown uses PHP. It runs on PHP 5.6 and later, but we recommend using the latest available version of PHP.
First, choose an existing project directory, likely a Git repository. We will call this the {$REPO} directory.
Next, use Composer to install a Bookdown skeleton as a subdirectory inside {$REPO}. We suggest _bookdown/ since Github Pages will not publish underscore-prefixed paths.
cd {$REPO}
composer create-project bookdown/project _bookdown/
You may wish to add the following lines to {$REPO}/.gitignore so that the underlying libraries are not committed to your main repository.
/_bookdown/vendor
The Bookdown skeleton includes an example to confirm that installation succeeded. Change into the skeleton directory, then issue the bookdown command to generate the example files:
cd _bookdown/
./vendor/bin/bookdown book/bookdown.json
You should see some output logs indicating file reading and creation. The HTML will be generated at the root of {$REPO}, not in the _bookdown subdirectory. You should see two files, index.html and example.html.
To browse these files, start the built-in PHP server on localhost:8080 (or some other port) and then use a web client to review them.
php -S localhost:8080 -t {$REPO}
Be sure to terminate the server when done.