# FastAPI CLI { #fastapi-cli }

**FastAPI CLI** is a command line program that you can use to serve your FastAPI app, manage your FastAPI project, and more.

When you install FastAPI (e.g. with `pip install "fastapi[standard]"`), it includes a package called `fastapi-cli`, this package provides the `fastapi` command in the terminal.

To run your FastAPI app for development, you can use the `fastapi dev` command:

<div class="termy">

```console

public interface ProtoSession {

    /**
     * Returns immutable user properties to use for interpolation. The user properties have been configured directly
     * by the user, e.g. via the {@code -Dkey=value} parameter on the command line.
     *
     * @return the user properties, never {@code null}
     */
    @Nonnull
    Map<String, String> getUserProperties();

    /**

 * specific language governing permissions and limitations
 * under the License.
 */

/**
 * This package contains the core classes for CLIng (CLI "new-gen"),
 * the next generation command-line interface for Maven.
 */

---

## FastAPI mini documentary

There's a <a href="https://www.youtube.com/watch?v=mpR8ngthqiE" class="external-link" target="_blank">FastAPI mini documentary</a> released at the end of 2025, you can watch it online:

<a href="https://www.youtube.com/watch?v=mpR8ngthqiE" target="_blank"><img src="https://fastapi.tiangolo.com/img/fastapi-documentary.jpg" alt="FastAPI Mini Documentary"></a>

## **Typer**, the FastAPI of CLIs

mvn formatter:format           # Format code
mvn license:format             # Update license headers
```

### Code Style

- 4 spaces (no tabs)
- Opening brace on same line
- Max line length: 120
- JavaDoc required for public APIs
- License headers required

### Testing

**Structure**: `src/test/java/org/codelibs/fess/crawler/`
**Frameworks**: JUnit 4, UTFlute, Mockito, Testcontainers

        serializer.setProperty("http://xmlpull.org/v1/doc/properties.html#serializer-indentation", "  ");
        serializer.setProperty("http://xmlpull.org/v1/doc/properties.html#serializer-line-separator", "\n");
        serializer.setOutput(writer);
        serializer.startDocument(coreExtensions.getModelEncoding(), null);
        writeCoreExtensions(coreExtensions, "extensions", serializer);

        }
    }

    @Override
    public void mojoSkipped(ExecutionEvent event) {
        if (logger.isWarnEnabled()) {
            init();
            logger.warn(
                    "Goal '{}' requires online mode for execution but Maven is currently offline, skipping",
                    event.getMojoExecution().getGoal());
        }
    }

    /**

Es gibt einen <a href="https://www.youtube.com/watch?v=mpR8ngthqiE" class="external-link" target="_blank">FastAPI-Mini-Dokumentarfilm</a>, veröffentlicht Ende 2025, Sie können ihn online ansehen:

<a href="https://www.youtube.com/watch?v=mpR8ngthqiE" target="_blank"><img src="https://fastapi.tiangolo.com/img/fastapi-documentary.jpg" alt="FastAPI Mini-Dokumentarfilm"></a>

        try {
            return CommonsCliEncryptOptions.parse(context.parserRequest.args().toArray(new String[0]));
        } catch (ParseException e) {
            throw new IllegalArgumentException("Failed to parse command line options: " + e.getMessage(), e);
        }
    }

	ErrSyntax        = DecoderError{msg: "invalid character"}
	ErrUnexpectedEOF = DecoderError{msg: "unexpected end of JSON input"}
	ErrMaxDepth      = DecoderError{msg: "maximum recursion depth exceeded"}
)

type errPos [2]int // line number, byte offset where error occurred

// DecoderError contains a detailed decoding error.
type DecoderError struct {
	msg       string // description of error
	context   string // additional error context