# The serve command

The serve command is used to preview a book by serving it over HTTP at `localhost:3000` by default. Additionally it watches the book's directory for changes, rebuilding the book and refreshing clients for each change. A websocket connection is used to trigger the client-side refresh.

Note: The `serve` command is for testing a book's HTML output, and is not intended to be a complete HTTP server for a website.

#### Specify a directory

The `serve` command can take a directory as an argument to use as the book's root instead of the current working directory.

    mdbook serve path/to/book

#### Server options

`serve` has four options: the HTTP port, the WebSocket port, the HTTP hostname to listen on, and the hostname for the browser to connect to for WebSockets.

For example: suppose you have an nginx server for SSL termination which has a public address of 192.168.1.100 on port 80 and proxied that to 127.0.0.1 on port 8000. To run use the nginx proxy do:

    mdbook serve path/to/book -p 8000 -n 127.0.0.1 --websocket-hostname 192.168.1.100

If you were to want live reloading for this you would need to proxy the websocket calls through nginx as well from `192.168.1.100:<WS_PORT>` to `127.0.0.1:<WS_PORT>`. The `-w` flag allows for the websocket port to be configured.

#### --open

When you use the `--open` (`-o`) flag, mdbook will open the book in your default web browser after starting the server.

#### --dest-dir

The `--dest-dir` (`-d`) option allows you to change the output directory for the book. Relative paths are interpreted relative to the book's root directory. If not specified it will default to the value of the `build.build-dir` key in `book.toml`, or to `./book`.

#### Specify exclude patterns

The `serve` command will not automatically trigger a build for files listed in the `.gitignore` file in the book root directory. The `.gitignore` file may contain file patterns described in the gitignore documentation. This can be useful for ignoring temporary files created by some editors.

Note: Only `.gitignore` from book root directory is used. Global `$HOME/.gitignore` or `.gitignore` files in parent directories are not used.