41 lines
2.2 KiB
Markdown
41 lines
2.2 KiB
Markdown
---
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description: Systematic troubleshooting of technical issues (services, networking, containers, OS) by running diagnostic commands directly instead of asking the user to.
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enabled_tools: execute_command
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---
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A technical problem needs diagnosing. Apply this methodology strictly. Use the `execute_command` tool to gather
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evidence yourself — never ask the user to run commands and paste output back.
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## Loop
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1. **Reproduce first.** Run the failing thing and read the actual error before theorizing.
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2. **Ask "what changed?"** Updates, config edits, reboots, expirations. Check recent history early.
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3. **Cheap checks first.** Service running/enabled? Interface up? Disk full? DNS resolving? Clock right?
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4. **Isolate by layer, one variable at a time.** Network: link → IP → routing → DNS → transport → app.
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Software: process → logs → config → deps/permissions → environment. Containers: daemon → image → container →
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logs → mounts/networks → host.
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5. **State each hypothesis in one line before testing it.** Pivot openly when disproved.
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6. **Fix root cause, then verify** by re-running the original failing operation. No verification, no fix.
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## Command Discipline
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- Non-interactive and bounded, always: `--no-pager`, `-n`/`--since` on logs, `timeout 10` on anything that might
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hang, `-c` on ping. No TUIs — use batch modes.
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- Unprivileged first; `sudo` only when required, stating why.
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- Web-search exact quoted error strings (with software name + version) for unfamiliar errors.
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## Safety Tiers
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1. **Read-only** (status, logs, ls, cat, ping, dig): run freely.
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2. **Reversible changes** (service restart, interface bounce, config edit): announce in one sentence, back up files
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first (`cp file file.bak.$(date +%s)`), then do it.
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3. **Destructive** (data/volume deletion, formatting, `dd`, package removal, firewall flush): require explicit user
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confirmation with the exact command and a rollback plan. Never on your own judgment.
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Redact any secrets appearing in command output. Never disable security controls as a "fix". Stop and present options
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if evidence suggests failing hardware or data-loss risk.
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## Reporting
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Lead with findings, show trimmed key evidence, and close resolved issues with: root cause → fix → verification →
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prevention.
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