linux-sysadmin

A set of guided workflows for administering Debian and Ubuntu Linux machines. It uses standard tools such as apt for packages, systemd for services, and journalctl for logs.

In plain words
What is it for?
Checking users, SSH, firewalls, updates, open ports, permissions, logs, backups, CPU, memory, storage, processes, services, and system settings.
Why use it?
It provides a structured way to investigate security, performance, service failures, and maintenance tasks while requiring confirmation before risky changes.

Cursor rule for Cursor

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 rules/hermeticormus/linux-sysadmin-skills/linux-sysadmin
Clone the repo
git clone --depth 1 https://github.com/HermeticOrmus/linux-sysadmin-skills

Made for: Cursor.

Per session 33 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 404 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 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 $0.00033 $0.00404
Opus 5 $0.00016 $0.00202
Sonnet 5 $0.00007 $0.00081
Haiku 4.5 $0.00003 $0.00040

Measured yesterday against content hash 5cab2548bc78, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

linux-sysadmin scanned grade A with 0 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 yesterday.

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.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.cursor/rules/linux-sysadmin.mdc · 31 lines

What it actually says

Linux sysadmin workflows

Five checklist-driven system administration workflows for Debian/Ubuntu-family machines. Package operations use apt; service and log operations use systemd and journalctl.

Safety rule: confirm before any destructive operation. Removing packages, editing SSH or firewall config, changing kernel parameters, killing processes, and clearing caches are explained first (including lock-out risk) and wait for approval. Read-only inspection runs without prompting.

1. Security

Audit and harden: user and access control, SSH hardening, firewall (UFW), updates and patches, services and open ports, file permissions (including SUID/SGID), logs, application and network security, backups. Explain each change's security benefit and lock-out risk before applying.

2. Performance

Assess CPU, memory, disk, network, and processes. Identify the bottleneck before tuning. Apply targeted changes (kernel parameters in /etc/sysctl.conf, service trimming, resource limits) and measure before and after.

3. Diagnose

Hypothesis-driven loop for a failing service or issue: describe the problem, gather evidence (journalctl -xe, systemctl status <service>), find patterns, check recent changes, form and test a hypothesis, apply the fix, verify resolution.

4. Monitor

Read-only health sweep: CPU, memory, disk, network, processes, critical services, temperatures, recent log errors. End with a summary that flags concerns. Make no changes.

5. Maintain

Routine pass: apt update && apt upgrade, apt autoremove, clean cache, scan logs (journalctl -p 3 -b), check disk (df -h), verify critical services, confirm backups. Ask before destructive steps.

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. yesterday First seen · 31 lines · 33 tokens per session scan A 5cab2548bc78

Subscribe to this mod's changes

linux-sysadmin is a cursor rule published in the GitHub repository HermeticOrmus/linux-sysadmin-skills (2 stars, last pushed 3mo ago), licensed MIT. It adds 33 tokens to every session and 404 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.