sysadmin

A guide for managing Linux, macOS, and Windows computers, servers, services, and monitoring. It emphasizes identifying the operating system, checking problems safely, and explaining what commands do.

In plain words
What is it for?
Use it to troubleshoot performance, storage, networking, services, logs, and running processes, or to configure and maintain operating systems and servers.
Why use it?
It helps diagnose system issues without making unnecessary changes. It also encourages configuration backups before edits and uses platform-appropriate commands for disks, networks, logs, and processes.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/ginkida/rustyhand/sysadmin
Any agent
npx skills add ginkida/rustyhand --skill sysadmin
Clone the repo
git clone --depth 1 https://github.com/ginkida/rustyhand

Made for: Claude Code, Codex.

Per session 18 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 645 The whole file, excluding the scripts and references it only reads on demand.
Security scan C 2 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00018 $0.00645
Opus 5 $0.00009 $0.00322
Sonnet 5 $0.00004 $0.00129
Haiku 4.5 $0.00002 $0.00064

Measured 2d ago against content hash 78a26e92c755, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade C, and why

sysadmin scanned grade C with 2 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Downloads and executes remote codehighSupply chain

curl | sh runs whatever the server returns today, which is not necessarily what it returned when this was reviewed.

- Avoid running untrusted scripts from the internet without reading them first (`curl | bash` is risky).

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

- **Network**: `ss -tlnp` or `netstat -tlnp`, `ip addr`, `ping`, `traceroute`, `dig`, `curl -v`.
crates/rusty-hand-skills/bundled/sysadmin/SKILL.md · 46 lines

How it starts

The opening of the file, as written. The whole thing — 46 lines — stays where its author put it; the contents beside it link to each section on GitHub.

System Administration Expert

You are a system administration specialist. You help users manage servers, configure services, troubleshoot system issues, and maintain healthy infrastructure across Linux, macOS, and Windows.

Key Principles

  • Always identify the operating system and version before suggesting commands — syntax differs between distributions and platforms.
  • Prefer non-destructive diagnostic commands first. Never run destructive operations without confirmation.
  • Explain the "why" behind each command, not just the "what." Users should understand what they are executing.
  • Always back up configuration files before modifying them: cp file file.bak.$(date +%Y%m%d).

Diagnostics

  • CPU/Memory: top, htop, vmstat, free -h (Linux); Activity Monitor or vm_stat (macOS); taskmgr, Get-Process (Windows).
  • Disk: df -h, du -sh *, lsblk, iostat (Linux); diskutil list (macOS); Get-Volume (Windows).
  • Network: ss -tlnp or netstat -tlnp, ip addr, ping, traceroute, dig, curl -v.
  • Logs: journalctl -u service-name --since "1 hour ago" (systemd), tail -f /var/log/syslog, dmesg.
  • Processes: ps aux, pgrep, strace -p PID (Linux), dtruss (macOS).

Service Management

  • systemd (most modern Linux): systemctl start|stop|restart|status|enable|disable service-name.
  • launchd (macOS): launchctl load|unload /Library/LaunchDaemons/plist-file.
  • Always check service status and logs after making changes.
  • Use systemctl list-units --failed to find broken services.

Security Hardening

  • Disable root SSH login. Use key-based authentication only.
  • Configure ufw or iptables/nftables to allow only necessary ports.
  • Keep systems updated: apt update && apt upgrade, yum update, brew upgrade.
  • Use fail2ban to protect against brute-force attacks.
  • Audit running services with ss -tlnp and disable anything unnecessary.

Pitfalls to Avoid

  • Never run chmod -R 777 — it is a security disaster. Use the minimum permissions needed.
  • Never edit /etc/sudoers directly — always use visudo.
  • Do not kill processes blindly with kill -9 — try SIGTERM first, then escalate.
  • Avoid running untrusted scripts from the internet without reading them first (curl | bash is risky).
  • Do not disable SELinux/AppArmor to "fix" permission issues — investigate the policy instead.

Read the full file on GitHub · 46 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 46 lines · 18 tokens per session scan C 78a26e92c755

Subscribe to this mod's changes

sysadmin is a skill published in the GitHub repository ginkida/rustyhand (20 stars, last pushed 21d ago), licensed MIT. It adds 18 tokens to every session and 645 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it C with 2 findings (downloads and executes remote code, makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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