# Disk Usage

> This skill should be used when the user asks to "check disk usage", "is my drive full", "what's using my disk", "disk space", "free up space", or mentions low storage. Reports free space, largest directories, caches, Time Machine local snapshots, Xcode simulator footprint, and node_modules sizes, then writes a JSON result to ~/.mac-guardian/data/.

- Skill: `dennisonbertram/disk-usage` (Agent Skill)
- Install (CLI): `npx skillmds@latest add dennisonbertram/disk-usage`
- Raw SKILL.md: https://api.skillmd.com/api/skills/dennisonbertram/disk-usage/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: dennisonbertram (https://skillmd.com/u/dennisonbertram)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/dennisonbertram/disk-usage

---


# disk-usage

Surveys storage usage on macOS without deleting anything.

## When to invoke

Trigger on phrases like: "check disk usage", "is my drive full", "what's using my disk", "disk space", "free up space".

## What to check

**1. Per-volume free space** — `df -h`. Filter to `apfs` and `hfs` volumes. For each volume:

- `/` free ≥ 20 GB or ≥ 15%: `ok`.
- `/` free 10–20 GB or 5–15%: `info`.
- `/` free 5–10 GB or 2–5%: `warn`.
- `/` free < 5 GB or < 2%: `critical`.

**2. Top 20 home directories by size** — `du -shx ~/* 2>/dev/null | sort -rh | head -20`. Record as raw. Individual dirs ≥ 50 GB get an `info` finding.

**3. Library caches** — `du -shx ~/Library/Caches 2>/dev/null`. If ≥ 20 GB, `info` "Library caches at <size>".

**4. System / user log sizes** — `du -shx ~/Library/Logs /private/var/log 2>/dev/null`. Record in raw.

**5. Time Machine local snapshots** — `tmutil listlocalsnapshots / 2>/dev/null`. Report the count. ≥ 10 snapshots: `info`.

**6. Xcode / iOS simulator footprint** — `du -shx ~/Library/Developer/CoreSimulator/Devices ~/Library/Developer/Xcode/DerivedData ~/Library/Developer/Xcode/iOS\ DeviceSupport 2>/dev/null`. Sum ≥ 30 GB: `info`. Sum ≥ 100 GB: `warn`.

**7. node_modules across common dev roots (optional and guarded)** — only run when the user's home has a `Develop/` or `Projects/` or `code/` directory: `find ~/Develop ~/Projects ~/code -type d -name node_modules -maxdepth 6 -prune -exec du -shx {} + 2>/dev/null | sort -rh | head -20`. Guard this with a soft timeout (use `timeout 60s` if `gtimeout` or coreutils `timeout` is available; otherwise include only if `find` completes within reason, and skip with an `info` finding "skipped — search would take too long" if not).

**8. Large Downloads / Trash** — `du -shx ~/Downloads ~/.Trash 2>/dev/null`. Each ≥ 10 GB: `info`.

## Output contract

Standard envelope. Write to `~/.mac-guardian/data/disk-usage-<ISOdate>.json`.

Top-level severity = max across all checks. Summary example: "44 GB free on / (warn). Biggest: ~/Library/Caches 38 GB, DerivedData 27 GB."

## Handoff

- On direct invocation: `bash ${CLAUDE_PLUGIN_ROOT}/scripts/render-single.sh disk-usage`.
- When invoked by `daily-health-report`, return JSON path only.

## Safety

- Read-only. Never delete caches, snapshots, DerivedData, or node_modules.
- If the user asks to clean up after seeing the report, explain what the commands would be and prompt for confirmation.
- Do not call `sudo`.