Methodology for macOS Disk Space Investigation | Generated by AI
Here’s the methodology:
1. Start broad — where is the space?
df -h /
Shows total disk, used, and available. This tells you how urgent it is and sets a baseline to measure against.
2. Top-level home directory scan
du -sh ~/* ~/.* 2>/dev/null | sort -rh | head -20
du -sh = disk usage, summarized, human-readable. This reveals which top-level directories are the biggest — typically ~/Library, ~/projects, ~/.cargo, etc. You drill into the biggest ones next.
3. Known macOS hotspots
These are locations that commonly accumulate junk on macOS. You check each one:
# App caches (safe to delete, apps rebuild them)
du -sh ~/Library/Caches/* 2>/dev/null | sort -rh | head -20
# App logs
du -sh ~/Library/Logs/* 2>/dev/null | sort -rh | head -10
# Docker VM image (huge even when Docker isn't running)
du -sh ~/Library/Containers/com.docker.docker 2>/dev/null
# Homebrew installed packages + cached downloads
du -sh /opt/homebrew 2>/dev/null
du -sh /opt/homebrew/Cellar/* 2>/dev/null | sort -rh | head -10
du -sh ~/Library/Caches/Homebrew/downloads/* 2>/dev/null | sort -rh | head -5
# Language-specific caches
du -sh ~/.npm ~/.yarn ~/.bun ~/.cargo ~/.rustup 2>/dev/null | sort -rh
du -sh ~/Library/Caches/pip 2>/dev/null
# JetBrains IDEs (caches + app support)
du -sh ~/Library/Caches/JetBrains 2>/dev/null
du -sh ~/Library/Application\ Support/JetBrains 2>/dev/null
# Xcode
du -sh ~/Library/Developer/Xcode/* 2>/dev/null | sort -rh
The pattern: du -sh <path>/* | sort -rh | head -N — list all children, sort by size descending, show top N.
4. Project build artifacts (often the biggest)
# Rust target dirs — massive, rebuildable
du -sh ~/projects/*/target 2>/dev/null | sort -rh
# Node modules
du -sh ~/projects/*/node_modules 2>/dev/null | sort -rh
These are the #1 space hog for developers. A single cargo build can produce 5-27GB in target/.
5. Find recently modified large files
find ~ -type f -size +100M -mtime -7 2>/dev/null
This catches things actively growing — files over 100MB modified in the last 7 days. If disk keeps growing, run this and look for patterns (same file getting bigger, or new files appearing in the same directory).
6. Monitor live writes (if still growing)
sudo fs_usage -w -f disk 2>/dev/null | head -50
This is a macOS-specific tool that watches filesystem activity in real-time. Shows exactly which process is writing to which file. Useful when you can’t figure out what’s eating space.
Summary of the pattern
df -h # how bad is it?
du -sh ~/* | sort -rh # where are the big dirs?
du -sh <bigdir>/* | sort -rh # drill into each big dir
find ~ -size +100M -mtime -7 # what's growing recently?
fs_usage # what's writing right now?
It’s just repeated du -sh | sort -rh drilling down from biggest to smallest, combined with domain knowledge of where macOS/dev tools stash their junk.