# Lg Ssh Controller > Guides SSH command implementation for LG rig communication — connection setup, command execution, file transfer, error recovery, and multi-screen management via dartssh2. Use when this capability is needed. - Skill: `tomevault-io/lg-ssh-controller` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/lg-ssh-controller` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/lg-ssh-controller/raw - Safety review: pending - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Coding & Dev Tools - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/lg-ssh-controller --- # LG SSH Controller Guides implementation of SSH-based communication between the Flutter controller app and the Liquid Galaxy rig. Every LG operation — KML display, camera control, rig management — flows through SSH. **Announce:** "SSH Controller activated. Setting up secure communication with the LG rig." ## When to Invoke - During `lg-logic-builder` when implementing the SSH service layer. - When a student needs to add new SSH commands for rig interaction. - When debugging SSH connection or command execution issues. ## Core SSH Commands | Command | Purpose | Target | Dart Method | |---------|---------|--------|-------------| | `echo "flytoview=..." > /tmp/query.txt` | Fly camera to location | Master | `flyTo(lat, lon, alt, tilt, heading)` | | `echo "search=..." > /tmp/query.txt` | Search for place | Master | `search(query)` | | KML upload via SFTP | Display geographic data | Master | `sendKML(kmlString)` | | `echo "..." > /var/www/html/kmls.txt` | Load KML files via NetworkLink | Master | `loadKML(filename)` | | `echo "" > /var/www/html/kml/slave_.kml` | Clear KML on slave screen | Slave N | `clearKML(slaveN)` | | `echo '...' > /var/www/html/kml/slave_.kml` | Send logo overlay to slave | Slave N | `sendLogo(slaveN, kml)` | | `sshpass -p lg ssh lg@lg "killall googleearth-bin; ..."` | Relaunch Google Earth | All | `relaunchGE()` | | `sshpass -p lg ssh lg@lg "sudo reboot"` | Reboot machine | All | `reboot()` | ## Connection Parameters ```dart /// Default LG rig connection settings class LGConnection { static const String defaultHost = '192.168.56.101'; static const int defaultPort = 22; static const String defaultUser = 'lg'; static const String defaultPassword = 'lg'; static const int defaultScreens = 3; } ``` **IMPORTANT**: These defaults are for the **LG Docker/VM test environment**. Real rig IPs vary. Always use `config.dart` or the Connection Settings screen to make these configurable. ## LG Rig Topology (3-screen default) ``` ┌─────────┐ ┌─────────┐ ┌─────────┐ │ lg3 │ │ lg1 │ │ lg2 │ │ LEFT │ │ MASTER │ │ RIGHT │ └─────────┘ └─────────┘ └─────────┘ ``` - **lg1 (Master)**: Runs Google Earth primary instance. Receives commands via SSH. - **lg2 (Right slave)**: Typically displays the app logo via ScreenOverlay. - **lg3 (Left slave)**: Additional context/placemarks. - **Slave KML paths**: `/var/www/html/kml/slave_.kml` where n = screen number. ### Screen Number Calculation ```dart /// Calculate right-most slave screen number for logo placement int get rightMostSlave => (totalScreens ~/ 2) + 1; /// Calculate left-most slave int get leftMostSlave => totalScreens; /// Calculate all slave numbers (excluding master = 1) List get slaveNumbers => List.generate(totalScreens - 1, (i) => i + 2); ``` ## SSH Service Implementation Pattern ```dart import 'package:dartssh2/dartssh2.dart'; class SSHService extends ChangeNotifier { SSHClient? _client; bool _connected = false; bool get connected => _connected; /// Connect to the LG master node Future connect({ required String host, required int port, required String username, required String password, }) async { try { final socket = await SSHSocket.connect( host, port, timeout: const Duration(seconds: 10), ); _client = SSHClient( socket, username: username, onPasswordRequest: () => password, ); _connected = true; notifyListeners(); return true; } catch (e) { _connected = false; notifyListeners(); return false; } } /// Execute a command on the LG rig Future execute(String command) async { if (_client == null) throw Exception('Not connected to LG rig'); final result = await _client!.run(command); return utf8.decode(result); } /// Disconnect and clean up void disconnect() { _client?.close(); _client = null; _connected = false; notifyListeners(); } @override void dispose() { disconnect(); super.dispose(); } } ``` ## Error Recovery | Failure | Recovery Strategy | |---------|-------------------| | Connection timeout | Auto-reconnect with exponential backoff (1s, 2s, 4s, max 16s) | | Authentication failure | Show error + open Connection Settings screen | | Command timeout | Retry once after 5s, then report error to UI | | SFTP failure | Fallback to `echo '...' >` command for small payloads | | Rig unreachable | Verify network, show "Check that rig is on the same WiFi" | ## ⛔️ Student Interaction — MANDATORY **After implementing the SSH service, STOP and walk through with the student:** 1. Explain the connection lifecycle: connect → verify → execute → cleanup → disconnect. 2. Show what happens on the **rig side** when each command runs (file written, GE reads it). 3. Ask: *"What happens if the app is closed without calling disconnect()? Why do we need dispose()?"* 4. If the student cannot trace the SSH flow, link to **lg-learning-resources** (.agent/skills/lg-learning-resources/SKILL.md) — SSH & LG Communication topic. **DO NOT move to KML commands** until the student understands the connection lifecycle. ## Reference Links - **Lucia's SSHService implementation**: https://github.com/LiquidGalaxyLAB/LG-Master-Web-App - **dartssh2 package**: https://pub.dev/packages/dartssh2 - **LG SSH command reference**: https://github.com/LiquidGalaxyLAB/liquid-galaxy/wiki - **LG Rig setup scripts**: https://github.com/LiquidGalaxyLAB/liquid-galaxy - For deeper study → **lg-learning-resources** (.agent/skills/lg-learning-resources/SKILL.md) ## Handoff After SSH service implementation → **lg-kml-writer** (.agent/skills/lg-kml-writer/SKILL.md) for KML generation, then **lg-code-reviewer** (.agent/skills/lg-code-reviewer/SKILL.md) for quality check. ## 🔗 Skill Chain After the SSH service is implemented and the student understands the connection lifecycle, **automatically offer the next stage**: > *"SSH communication is wired up! The app can now talk to the LG rig securely. Let's get this reviewed for error handling and resource cleanup. Ready for the Code Review? 🔍"* If student says "ready" → activate `.agent/skills/lg-code-reviewer/SKILL.md`. --- > Converted and distributed by [TomeVault](https://tomevault.io/claim/ashishyesale7) — claim your Tome and manage your conversions.