name: linux-admin
version: 1.0.0
description: Linux system administration for KHY-Quant OS deployment — systemd services, networking, disk management, security hardening. Triggered for system management tasks.
layer: system
lifecycle: operations
tags: [linux, sysadmin, systemd, networking, filesystem, security]
platforms: [khy-quant, claude-code, cosh]
dependencies: []

Linux System Administration#

System management skill for KHY-Quant OS deployments.

When to Activate#

User manages systemd services (start/stop/enable/disable)
User configures networking (firewall, DNS, ports)
User manages disk, filesystems, or storage
User asks about system resource monitoring
User performs security hardening or user management

Core Principles#

Least privilege — run services as dedicated users, not root
Idempotent scripts — running twice produces the same result
Audit trail — log all configuration changes

Common Tasks#

Service Management#

# KHY-Quant backend service
sudo systemctl status khy-backend
sudo systemctl restart khy-backend
journalctl -u khy-backend -f --no-pager

Port Management#

# Check what's using a port
ss -tlnp | grep :3000
# Open firewall port
sudo firewall-cmd --add-port=3000/tcp --permanent
sudo firewall-cmd --reload

Disk Usage#

df -h
du -sh /home/*/KHY-Quant* 2>/dev/null

Process Monitoring#

# Find Node.js processes
pgrep -af node
# System resource overview
top -bn1 | head -20

Safety Rules#

Never run rm -rf / or delete system directories
Always back up config files before modifying
Use --dry-run flags when available
Check disk space before large operations