I freed 80GB on my Mac with a bash script — no app, no subscription

My Mac mini was telling me I had over 80GB of "System Data" to free up. CleanMyMac wanted €34/year. DaisyDisk wanted €10 just to tell me where the files were.

So I spent an evening writing a bash script instead.

The problem with "System Data" on macOS

If you've ever opened System Settings → General → Storage and seen a huge "System Data" slice, you know the feeling. macOS is notoriously vague about what's in there.

The real culprits are usually:

• Time Machine local snapshots — macOS keeps these silently on your SSD, often tens of GB
• Xcode DerivedData and archives — rebuilds from old projects you haven't touched in months
• Game data from titles you uninstalled ages ago
• iMazing or other backup apps storing full iPhone backups locally
• App caches that grow indefinitely and are never cleaned automatically

None of these show up clearly in Finder. You need to know where to look.

Step 1: find out where your space went

Before deleting anything, I built a diagnostic tool that uses Spotlight (mdfind) to instantly find files over 500 MB — no slow full-disk scan, results in seconds.

bash mac-find-space.sh

On my Mac it found, among other things:

• A 25 GB Windows 11 virtual machine I hadn't booted in months
• 22 GB of iMazing backups duplicating what was already on iCloud
• 6.5 GB of Magic: The Gathering Arena downloads from a game I quit playing
• 4.9 GB of macOS aerial wallpaper cache
• Several GB of Time Machine local snapshots that macOS never told me about

Total: over 80 GB of recoverable space, none of it visible at a glance.

Step 2: clean it safely

The main script — macos-cleanup.sh — runs in dry-run mode by default. It shows you everything it would delete without touching a single file.

# Preview (safe, nothing is deleted)
bash macos-cleanup.sh

# Clean interactively
bash macos-cleanup.sh --clean

# Clean everything automatically
bash macos-cleanup.sh --clean --yes

Here's what a dry-run looks like:

══════════════════════════════════════════════════════════
  🍎  macOS Cleanup Utility
══════════════════════════════════════════════════════════
  MODE: DRY-RUN — nothing will be deleted
  Disk free before: 4.8 GB
══════════════════════════════════════════════════════════

[1] User caches  ~/Library/Caches
  [DRY-RUN]  ~/Library/Caches                              2.1 GB

[2] Logs
  [DRY-RUN]  ~/Library/Logs                               1.6 GB
  [DRY-RUN]  /Library/Logs                               23 MB
...

What it cleans

What it never touches

• iCloud Drive and OneDrive synced files
• iOS backups (shows size info only — remove via Finder)
• macOS system files
• Your documents, photos, downloads

Why not just use CleanMyMac?

Nothing wrong with it — it's a polished app. But:

• It costs money every year
• It runs in the background
• You can't read its source code
• It has more features than most people need

This script is ~200 lines of readable bash. You can open it, read every line, and know exactly what it does before running it. No black box.

Get it

git clone https://github.com/dadu14-code/mac-janitor.git
cd mac-janitor
bash mac-find-space.sh      # find out where your GBs went
bash macos-cleanup.sh       # preview what would be cleaned
bash macos-cleanup.sh --clean  # clean when ready

GitHub: dadu14-code/mac-janitor

Tested on macOS Ventura, Sonoma and Sequoia. Pure bash, no dependencies, MIT license.

Feedback welcome — especially if you find new paths worth cleaning or test it on older macOS versions. PRs are open.