CLI Reference¶

Nemo is invoked from the command line. This page documents all available options.

Usage¶

nemo [OPTIONS]

Options¶

Option	Short	Default	Description
`--app-config <PATH>`	`-c`	`app.xml`	Path to the main XML configuration file
`--app-config-dirs <DIR>`	`-d`		Additional configuration directories to scan (repeatable)
`--extension-dirs <DIR>`	`-e`		Extension/plugin directories to load (repeatable)
`--verbose`	`-v`		Enable debug-level logging
`--headless`			Run without opening a window
`--validate-only`			Parse and validate config, then exit
`--help`	`-h`		Print help information
`--version`	`-V`		Print version

Examples¶

Run an application¶

nemo --app-config app.xml

Run with verbose logging¶

nemo -c app.xml --verbose

Validate configuration without launching¶

nemo -c app.xml --validate-only

This parses the XML file, checks for syntax errors and schema violations, then exits. Useful in CI pipelines or before deploying configuration changes.

Run in headless mode¶

nemo -c app.xml --headless

Starts data sources and event handling without opening a window. Useful for background data processing or testing. Press Ctrl-C to stop.

Load additional config and extension directories¶

nemo -c app.xml -d ./config.d -e ./plugins -e ./scripts

Multiple directories can be specified by repeating the flag. Config directories are scanned for additional XML files. Extension directories are scanned for .rhai scripts and native plugin libraries.

Exit Codes¶

Code	Meaning
0	Success (including `--validate-only` with valid config)
1	Configuration error (parse, validation, or resolution failure)
1	Runtime error (failed to initialize subsystems)

Environment¶

Nemo reads environment variables in XML expressions via the ${env.VARIABLE_NAME} syntax. No special environment variables are required by Nemo itself.

Logging¶

Nemo uses tracing for structured logging. Output goes to stderr.

Default level: INFO
With --verbose: DEBUG

Log output includes thread IDs and module targets for troubleshooting:

2026-02-09T12:00:00.000Z  INFO nemo: Nemo v0.1.0 starting...
2026-02-09T12:00:00.001Z  INFO nemo::runtime: Loading configuration from: "app.xml"
2026-02-09T12:00:00.010Z  INFO nemo::runtime: Initializing subsystems...
2026-02-09T12:00:00.015Z  INFO nemo: Starting GPUI application...