| name | kos-programming |
| description | Comprehensive knowledge base for kOS (Kerbal Operating System), the programmable scripting mod for Kerbal Space Program. Covers the KerboScript language, core features, bound variables, flight control, maneuver nodes, math library, file system, boot files, triggers, and community resources. Compiled from official kOS documentation (v1.4.0.0), KSP-KOS GitHub, Reddit r/Kos, and SpaceDock.ru community guides.
|
| author | Acea |
| sources | ["https://ksp-kos.github.io/KOS/","https://github.com/KSP-KOS/KOS","https://www.reddit.com/r/Kos/","https://spacedock.ru/kerbal-space-program/guides-ksp/","/opt/data/workspace/20260617/KSPWorldKnowledge/kspWorldKnowledge.skill"] |
| category | gaming |
| version | 1 |
| last_updated | "2026-06-17T00:00:00.000Z" |
| applies_when | directory_exists:GameData/kOS |
kOS Programming — Kerbal Operating System Knowledge Base
⚠ CONDITIONAL SKILL: This knowledge base applies only when kOS is installed in the current KSP instance. To verify: check that the directory GameData/kOS exists within the KSP installation folder. If this directory is not present, the information below may not be relevant to the user's current setup.
Detection method:
ls -d <KSP_ROOT>/GameData/kOS 2>/dev/null && echo "kOS installed" || echo "kOS NOT installed"
Test-Path "<KSP_ROOT>\GameData\kOS" -PathType Container
This .skill file is a structured world knowledge base for LLM retrieval. For general KSP game mechanics, see ksp-world-knowledge.skill. For MechJeb (autopilot mod), see mechjeb.skill.
1. WHAT IS kOS?
kOS (Kerbal Operating System) is a community-supported mod for Kerbal Space Program that adds a fully programmable onboard computer to every spacecraft. Players write scripts in KerboScript, a domain-specific scripting language, to automate launch, orbital maneuvers, rendezvous, docking, landing, and more.
Philosophy: kOS is to programming what KSP is to rocket science — you don't have to know what you're doing to get started, but you'll learn by accident. It scales with your skill level.
2. INSTALLATION & SETUP
2.1 Install the Mod
Copy the contents of the kOS zip into your KSP folder — it installs into GameData/.
2.2 Add kOS Processor to a Vessel
In the VAB/SPH, find the Comptronix CX-4181 kOS processor part and attach it to your vessel. This is the hardware that runs scripts.
2.3 Open the Terminal
- Press [ (open bracket) to open the kOS terminal window
- The terminal is a text-based interface for typing commands directly
- Type
print "Hello Kerbin!" and press Enter to test
2.4 Boot Files
- Create a file named
boot.ks in the kOS volume (e.g., on the processor's disk)
- This script runs automatically when the vessel loads or launches
- Used for auto-configuration, staging setup, and pre-flight checks
3. KERBOSCRIPT LANGUAGE
Full language reference extracted to references/language-reference.md, covering syntax, types, variables, scoping, operators, control structures, user functions, and built-in name protection.
4. FLIGHT CONTROL
Flight control, triggers, maneuver nodes, and encounter/transfer code examples extracted to references/flight-and-maneuvers.md, covering steering, throttle, staging, RCS/SAS, action groups, WHEN/ON/WAIT triggers, maneuver node creation/execution, and transfer calculations.
5. BUILT-IN VARIABLES (BOUND VARIABLES)
Full reference tables for bound variables, math library, list operations, and file system extracted to references/reference-tables.md, covering ship/orbit/flight/resource/control variables, vector/trig/math functions, list methods, and file I/O.
6. MATH LIBRARY
Math library reference extracted to references/reference-tables.md, covering vector operations, trigonometric functions, math functions, and constants.
7. LIST OPERATIONS
List operations reference extracted to references/reference-tables.md, covering list creation and all list methods.
8. FILE SYSTEM
File system reference extracted to references/reference-tables.md, covering volumes, reading/writing, file methods, and JSON support.
9. TRIGGERS AND EVENTS
Trigger and event code examples extracted to references/flight-and-maneuvers.md, covering WHEN/ON triggers and WAIT commands.
10. MANEUVER NODES
Maneuver node code examples extracted to references/flight-and-maneuvers.md, covering node creation, execution, and common maneuvers.
11. ENCOUNTERS AND TRANSFERS
Encounter check and transfer window calculator code examples extracted to references/flight-and-maneuvers.md.
12. COMMON SCRIPTS
Ready-to-use script examples extracted to references/example-scripts.md:
- Launch Script — Standard launch-to-orbit sequence
- Gravity Turn — Dynamic pitch steering
- Landing Script — Retrograde suicide burn
13. ADDONS AND INTEGRATION
13.1 kOS.MechJeb2.Addon
Direct integration between kOS and MechJeb. Install via CKAN. For detailed API and usage, see mechjeb.skill §4.3.
13.2 kRPC Integration
- kIPC: Inter-Process Communication bridge between kOS and kRPC. For details, see krpc-programming.skill.
13.3 Other Addons
- kOS-EVA: Control Kerbals on EVA
- kOS-ScanSat: Integration with ScanSat mod
14. TIPS AND BEST PRACTICES
14.1 Script Organization
- Use
@LAZYGLOBAL OFF. at the top of scripts
- Define functions with
FUNCTION name { PARAMETER p1. ... }
- Use
RUNPATH("script.ks", arg1, arg2). for modular code
14.2 Performance
- Minimize
WAIT UNTIL in tight loops
- Cache frequently accessed values
- Use
WHEN triggers instead of polling where possible
14.3 Debugging
- Check the kOS terminal for error messages and stack traces
- Use
LIST commands to inspect variables, bodies, vessels, and parts in scope
- Use
LOG to write debug output to persistent files for post-flight analysis
14.4 Common Pitfalls
- Case insensitivity: Everything is case-insensitive
- Decimal points: Always use
. for decimal (not ,)
- Vector math: Remember vectors use parentheses:
V(x,y,z)
- Trigger scope:
WHEN triggers capture variables by reference, not by value
- @LAZYGLOBAL OFF: Requires explicit variable declarations
- Built-in protection: Cannot overwrite built-in names without
@CLOBBERBUILTINS
APPENDIX: QUICK REFERENCE
Essential commands and resource links extracted to references/quick-reference.md, covering PRINT/SET/LOCK/UNLOCK/RUN commands, LIST operations, and key documentation links.
