---
title: "Logging Privacy Shenanigans | Peter Steinberger"
url: https://stacklist.com/card/e7adbf53-10dc-4a93-bf1c-4af492e4f599
source_url: "https://steipete.me/posts/2025/logging-privacy-shenanigans"
stack: https://stacklist.com/stack/3963846b-8e78-4abf-8ffd-22398de43005
summary: "Apple's unified logging system redacts sensitive data as <private> in macOS logs, hiding crucial debugging information. The article explains the redaction behavior and provides practical solutions including using plist files in /Library/Preferences/Logging/Subsystems/ to enable private data visibility."
tags: "macos-logging, privacy-redaction, debugging, unified-logging, plist-configuration, swift-development"
key_entities: "Peter Steinberger (person), Rasmus Sten (person), macOS (technology), Swift (technology), os_log (technology), unified logging system (technology), privacy redaction (concept), logging configuration (concept), macOS Catalina (event)"
classification: "tutorial"
content_hash: "sha256:77d52d4d1d8b79083b811bc9efa0622dedc5bd2cafff4a607d74a0fd3717110b"
acp_version: "0.2"
token_counts_approximate: 2580
visibility: public
agent_accessible: true
status: "final"
---

# Logging Privacy Shenanigans | Peter Steinberger

TL;DR – Apple logs hide the juicy debugging bits as <private> . Drop plist files into /Library/Preferences/Logging/Subsystems/ for a simpler solution, or install a configuration profile as an alternative. If you’ve ever tried debugging a macOS app using the unified logging system, you’ve probably encountered the dreaded <private> redaction. Your carefully crafted log messages turn into cryptic puzzles where the most important debugging information is hidden. Let me show you what’s really going on and how to work around it. The Privacy Problem When you log something like this in Swift: logger. info ( " User \( username ) connected to session \( sessionId ) " ) You expect to see: User john.doe connected to session ABC-123-DEF But instead you get: User <private> connected to session <private> Not very helpful when you’re trying to debug an issue, right? What Actually Gets Redacted Here’s where it gets interesting. Through testing, I discovered that Apple’s redaction logic is not as straightforward as the documentation suggests: What you log Documentation says Reality Simple strings ( "user@example.com" ) Redacted Usually redacted! File paths ( /Users/username ) Redacted ✓ Redacted UUIDs ( ABC-123-DEF ) Redacted ✓ Redacted Integers, booleans, floats Public ✓ Public The discrepancy comes from how Apple’s logging system is implemented. The os_log function requires format strings to be compile-time constants (C string literals) for performance optimization. When you use string interpolation with dynamic values, the compiler and logging library work together to mark these as runtime data that needs privacy protection. Static strings embedded directly in your code are treated as part of the format string and assumed to be non-sensitive, while any runtime values (variables, computed properties, function returns) are automatically redacted to prevent accidental leakage of personal information. Old Solutions That No Longer Work Before we get to what works, let’s quickly cover what doesn’t work anymore: ❌ The private_data:on flag (Dead since Catalina) # This returns "Invalid Modes 'private_data:on'" on macOS 10.15+ sudo log config --mode " private_data:on " --subsystem your.app.subsystem This was completely removed in macOS Catalina (10.15) and later. ❌ sudo doesn’t reveal private data You might think running with sudo would show everything: sudo log show --predicate ' subsystem == "your.app" ' --info Nope! The privacy redaction happens at write time , not read time. Once logged as <private> , the actual data is gone forever. The Plist Solution (Preferred Method) Thanks to Rasmus Sten for pointing out this elegant solution! You don’t need to use .mobileconfig files – you can simply drop plist files directly into /Library/Preferences/Logging/Subsystems/ . This is actually what happens when you install a configuration profile anyway. Step 1: Create a Plist File Create a file named after your subsystem (e.g., com.mycompany.myapp.plist ) with this content: <? xml version = " 1.0 " encoding = " UTF-8 " ?> <! DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd" > < plist version = " 1.0 " > < dict > < key > DEFAULT-OPTIONS </ key > < dict > < key > Enable-Private-Data </ key > < true /> </ dict > </ dict > </ plist > Step 2: Install the Plist # Create the directory if it doesn't exist sudo mkdir -p /Library/Preferences/Logging/Subsystems/ # Copy your plist file sudo cp com.mycompany.myapp.plist /Library/Preferences/Logging/Subsystems/ # Set proper permissions sudo chmod 644 /Library/Preferences/Logging/Subsystems/com.mycompany.myapp.plist Important Gotcha : When writing these plist files programmatically, you must write them atomically . Write to a temporary file first, then use mv to move it into place. This ensures the logging subsystem sees a complete, valid plist file. Step 3: Generate Fresh Logs The configuration only affects new log entries. Run your app to generate fresh logs. Step 4: Remove After Debugging sudo rm /Library/Preferences/Logging/Subsystems/com.mycompany.myapp.plist Why This Method is Better Scriptable : Can be added/removed programmatically from shell scripts No UI interaction : No need to navigate System Settings Granular control : Enable/disable specific subsystems instantly CI/CD friendly : Perfect for automated testing environments Documentation This approach is documented in: Apple’s os_log(5) man page (run man 5 os_log in Terminal) Apple Developer Forums confirming the /Library/Preferences/Logging/Subsystems/ directory usage Der Flounder’s detailed analysis of macOS Sequoia’s logging configuration The Configuration Profile Solution (Alternative Method) If you prefer a GUI approach or need to deploy settings across multiple machines, you can still use configuration profiles: View Configuration Profile Template <? xml version = " 1.0 " encoding = " UTF-8 " ?> <! DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd" > < plist version = " 1.0 " > < dict > < key > PayloadContent </ key > < array > < dict > < key > PayloadDisplayName </ key > < string > ManagedClient logging </ string > < key > PayloadEnabled </ key > < true /> < key > PayloadIdentifier </ key > < string > com.yourapp.logging.EnablePrivateData </ string > < key > PayloadType </ key > < string > com.apple.system.logging </ string > < key > PayloadUUID </ key > < string > GENERATE-UUID-1 </ string > < key > PayloadVersion </ key > < integer > 1 </ integer > < key > System </ key > < dict > < key > Enable-Private-Data </ key > < true /> </ dict > < key > Subsystems </ key > < dict > < key > your.app.subsystem </ key > < dict > < key > DEFAULT-OPTIONS </ key > < dict > < key > Enable-Private-Data </ key > < true /> </ dict > </ dict > </ dict > </ dict > </ array > < key > PayloadDescription </ key > < string > This profile enables logging of private data for debugging. </ string > < key > PayloadDisplayName </ key > < string > Your App Private Data Logging </ string > < key > PayloadIdentifier </ key > < string > com.yourapp.PrivateDataLogging </ string > < key > PayloadOrganization </ key > < string > Your Organization </ string > < key > PayloadRemovalDisallowed </ key > < false /> < key > PayloadType </ key > < string > Configuration </ string > < key > PayloadUUID </ key > < string > GENERATE-UUID-2 </ string > < key > PayloadVersion </ key > < integer > 1 </ integer > </ dict > </ plist > Customizing the Profile Critical Components to Replace: UUIDs : Two unique identifiers are required: Replace GENERATE-UUID-1 and GENERATE-UUID-2 with actual UUIDs Generate with: uuidgen (run twice for two different UUIDs) Organization : Replace Your Organization with your actual organization or app name Subsystems : The most critical part! Replace your.app.subsystem with your actual logging subsystem(s): let logger = Logger ( subsystem : " com.mycompany.myapp " , category : " Network " ) In this example, "com.mycompany.myapp" is the subsystem you need to add. Multiple Subsystems : To enable private data for multiple subsystems, duplicate the subsystem structure: < key > Subsystems </ key > < dict > < key > com.mycompany.myapp </ key > < dict > < key > DEFAULT-OPTIONS </ key > < dict > < key > Enable-Private-Data </ key > < true /> </ dict > </ dict > < key > com.mycompany.myframework </ key > < dict > < key > DEFAULT-OPTIONS </ key > < dict > < key > Enable-Private-Data </ key > < true /> </ dict > </ dict > </ dict > Key Implementation Details: PayloadType values : The top-level PayloadType must be Configuration , while the inner PayloadType (in PayloadContent) must be com.apple.system.logging PayloadRemovalDisallowed : Keep this as false so you can easily remove the profile after debugging System section : Enables private data for system-level logs DEFAULT-OPTIONS : Required wrapper for subsystem options Save the customized file as EnablePrivateLogging.mobileconfig . Installing Configuration Profiles Double-click the .mobileconfig file Navigate to: macOS 15 (Sequoia) and later : System Settings → General → Device Management macOS 14 (Sonoma) and earlier : System Settings → Privacy & Security → Profiles Click “Install…” and authenticate Wait 1-2 minutes for the system to apply changes Removing Configuration Profiles Go back to the Profiles/Device Management section and click the minus (-) button. The Code-Level Solution For production apps, mark specific non-sensitive values as public: // This will always be visible logger. info ( " Session: \( sessionId, privacy : . public ) " ) // This remains private by default logger. info ( " Token: \( apiToken ) " ) This is the safest approach as you explicitly control what’s exposed. Automating with Claude Code Instead of manually editing configuration files, just give Claude Code this blog post URL and ask it to create a customized plist or profile for your app. Living in the future means your documentation can be both human-readable and agent-executable. Summary Apple’s log privacy is well-intentioned but can be frustrating during development. The plist approach is your best bet for debugging: Privacy redaction happens at write time sudo can’t recover what was never stored Direct plist files are simpler than configuration profiles Always remove debugging configurations when done For more details on this topic, check out: Apple’s os_log(5) man page – The authoritative source Howard Oakley’s excellent post – Deep dive into log privacy Der Flounder’s Sequoia analysis – Latest macOS changes Happy debugging, and may your logs be forever unredacted (but only when you need them to be)!