CLI Mode

When you pass arguments to your app, Repl dispatches the command and exits — standard CLI behavior.

Invocation

myapp <route> [arguments] [options]

Examples:

myapp client list
myapp client 42 show
myapp client 42 show --json

Output formats

Every command supports output format flags out of the box:

Flag	Output
(none)	Human-readable text / table
--json	JSON
--xml	XML
--yaml	YAML
--markdown	Markdown table

$ myapp contacts list --json
[
  { "id": 1, "name": "Alice" },
  { "id": 2, "name": "Bob" }
]

Help and discovery

--help is built in at every level:

$ myapp --help
Commands:
  client
  report

$ myapp client --help
Commands:
  client list
  client {id} show
  client {id} remove

Shell completion

Register Repl’s completion scripts to get tab completion in your shell:

# Auto-detect current shell
myapp completion install

# Explicit shell
myapp completion install --shell bash
myapp completion install --shell powershell
myapp completion install --shell zsh
myapp completion install --shell fish
myapp completion install --shell nu   # Nushell

This writes a managed block to the shell’s profile file. Tab completion then works for all routes, context segments, and option names.

Other commands:

myapp completion status         # show current installation status
myapp completion uninstall      # remove the managed block
myapp completion detect-shell   # show which shell was detected

The completion bridge (completion __complete) is hidden from --help — it is a protocol command used by the shell scripts.

Automatic installation — configure how completion is offered at startup:

SetupMode	Behavior
Manual (default)	User runs install explicitly
Prompt	Offers installation once on the first interactive startup
Auto	Installs automatically when a supported shell is detected

app.Options(o =>
{
    o.ShellCompletion.SetupMode = CompletionSetupMode.Prompt;
});

Response files

Any argument prefixed with @ is a response file:

myapp @deploy.rsp

deploy.rsp:

deploy
--environment
production
--region
us-east-1

Tokens are read one per line. Useful for long or repeatable invocations, and for passing arguments in CI without quoting issues. Response files are not recursive.

Machine-readable help

Add --help --json to get a structured help payload — useful for agents and tooling:

$ myapp client --help --json
{
  "name": "client",
  "commands": [
    { "route": "list", "description": "..." },
    { "route": "{id:int} show", "description": "..." }
  ]
}

Exit codes

Condition	Exit code
Success	0
All named errors — command not found, validation failure, cancellation, unhandled exception	1
Custom (explicit)	any N — use Results.Exit(N) in a handler to return an arbitrary code

All error conditions produce exit code 1 by default. To signal a specific failure mode to callers or scripts, return Results.Exit(N) from your handler with the code that makes sense for your application.

Next step

→ REPL Mode