The build command is used to render your book:
mdbook build
It will try to parse your SUMMARY.md file to understand the structure of your book
and fetch the corresponding files.
The rendered ouput will maintain the same directory structure as the source for convenience. Large books will therefore remain structured when rendered.
Like init, the build command can take a directory as argument to use instead of the current working directory.
mdbook build path/to/book
note: make sure to run the build command in the root directory and not in the src directory