Appendix B: Configuration File Locations

This appendix documents where configuration files are located on macOS, how they differ from Linux conventions, and where to find common settings.

macOS Directory Structure Overview

macOS uses a hybrid filesystem hierarchy combining traditional Unix paths with Apple-specific locations:

/
├── Applications/              # GUI applications
├── Library/                   # System-wide resources and preferences
├── System/                    # macOS system files (read-only with SIP)
├── Users/                     # User home directories
│   └── <username>/
│       ├── Applications/      # User-installed apps
│       ├── Desktop/
│       ├── Documents/
│       ├── Downloads/
│       ├── Library/           # User-specific preferences and data
│       └── ...
├── Volumes/                   # Mounted volumes
├── bin/                       # Essential user commands
├── etc/                       # System configuration (symlink to /private/etc)
├── private/                   # Actual location of /etc, /var, /tmp
├── sbin/                      # Essential system commands
├── tmp/                       # Temporary files (symlink)
├── usr/                       # Secondary hierarchy
│   ├── bin/                   # User commands
│   ├── lib/                   # Libraries
│   ├── local/                 # Locally installed software
│   └── share/                 # Architecture-independent data
└── var/                       # Variable data (symlink to /private/var)

Shell Configuration Files

Zsh (Default Shell)

File	Scope	Purpose
`/etc/zshenv`	System	Read for all zsh invocations
`/etc/zprofile`	System	Read for login shells
`/etc/zshrc`	System	Read for interactive shells
`/etc/zlogin`	System	Read after zprofile for login shells
`~/.zshenv`	User	User environment (all invocations)
`~/.zprofile`	User	User login shell setup
`~/.zshrc`	User	User interactive shell config
`~/.zlogin`	User	User post-login commands
`~/.zlogout`	User	Logout cleanup

Load order for interactive login shell:

/etc/zshenv
~/.zshenv
/etc/zprofile
~/.zprofile
/etc/zshrc
~/.zshrc
/etc/zlogin
~/.zlogin

Bash

File	Scope	Purpose
`/etc/profile`	System	Login shell initialization
`/etc/bashrc`	System	Non-login interactive shells
`~/.bash_profile`	User	Login shell (read instead of .profile)
`~/.bash_login`	User	Login shell (fallback)
`~/.profile`	User	Login shell (fallback if no .bash_profile)
`~/.bashrc`	User	Interactive non-login shells
`~/.bash_logout`	User	Logout cleanup

Note: On macOS, Terminal.app opens login shells by default, so ~/.bash_profile is used rather than ~/.bashrc. Many users source .bashrc from .bash_profile for consistency.

Shell-Agnostic

File	Purpose
`~/.inputrc`	GNU Readline configuration
`/etc/paths`	System PATH directories (one per line)
`/etc/paths.d/*`	Additional PATH directories
`/etc/manpaths`	Manual page paths
`/etc/manpaths.d/*`	Additional manual paths

Application Preferences (Property Lists)

macOS applications store preferences in property list (plist) files:

User Preferences

Location	Contents
`~/Library/Preferences/`	User app preferences (.plist files)
`~/Library/Preferences/ByHost/`	Machine-specific user preferences

Common preference files:

~/Library/Preferences/
├── com.apple.finder.plist           # Finder settings
├── com.apple.dock.plist             # Dock settings
├── com.apple.Terminal.plist         # Terminal.app settings
├── com.apple.Safari.plist           # Safari settings
├── .GlobalPreferences.plist         # Global user defaults
├── com.googlecode.iterm2.plist      # iTerm2 settings
└── com.microsoft.VSCode.plist       # VS Code settings

System Preferences

Location	Contents
`/Library/Preferences/`	System-wide app preferences
`/Library/Preferences/SystemConfiguration/`	Network and system config

Reading and Modifying Preferences

# Read all preferences for an app
$ defaults read com.apple.finder

# Read specific key
$ defaults read com.apple.finder ShowHardDrivesOnDesktop

# Write a preference
$ defaults write com.apple.finder ShowHardDrivesOnDesktop -bool true

# Delete a preference (revert to default)
$ defaults delete com.apple.finder ShowHardDrivesOnDesktop

# Export plist to XML (readable)
$ plutil -convert xml1 -o - ~/Library/Preferences/com.apple.finder.plist

# List all domains
$ defaults domains | tr ',' '\n'

Launch Agents and Daemons

Directories by Scope

Location	Runs As	Loaded When
`~/Library/LaunchAgents/`	Current user	User logs in
`/Library/LaunchAgents/`	Current user	User logs in
`/System/Library/LaunchAgents/`	Current user	User logs in (Apple only)
`/Library/LaunchDaemons/`	root (or specified user)	System boot
`/System/Library/LaunchDaemons/`	root	System boot (Apple only)

Example LaunchAgent Locations

~/Library/LaunchAgents/
├── com.example.myagent.plist        # User-installed agent
├── homebrew.mxcl.postgresql.plist   # Homebrew service
└── com.docker.helper.plist          # Docker helper

/Library/LaunchDaemons/
├── com.example.mydaemon.plist       # Third-party daemon
├── com.docker.vmnetd.plist          # Docker networking daemon
└── org.postgresql.postgres.plist    # PostgreSQL daemon

Managing Services

# List user agents
$ launchctl list

# Load an agent
$ launchctl load ~/Library/LaunchAgents/com.example.agent.plist

# Unload an agent
$ launchctl unload ~/Library/LaunchAgents/com.example.agent.plist

# Bootstrap (modern method)
$ launchctl bootstrap gui/$(id -u) ~/Library/LaunchAgents/com.example.agent.plist

# Bootout (modern method)
$ launchctl bootout gui/$(id -u)/com.example.agent

Application Support and Data

User Application Data

Location	Contents
`~/Library/Application Support/`	App data, caches, state
`~/Library/Caches/`	Cached data (safe to delete)
`~/Library/Logs/`	Application logs
`~/Library/Containers/`	Sandboxed app data
`~/Library/Group Containers/`	Shared data between related apps
`~/Library/Saved Application State/`	Window positions, open documents

Common Application Support paths:

~/Library/Application Support/
├── Code/                    # VS Code
├── Firefox/                 # Firefox profiles
├── Google/Chrome/           # Chrome profiles
├── Slack/                   # Slack data
├── iTerm2/                  # iTerm2 data
├── JetBrains/               # IntelliJ, PyCharm, etc.
└── com.apple.TCC/           # Privacy database

System Application Data

Location	Contents
`/Library/Application Support/`	System-wide app data
`/Library/Caches/`	System caches
`/Library/Logs/`	System and app logs

Development Tools

Xcode and Command Line Tools

Location	Contents
`/Applications/Xcode.app/`	Xcode IDE
`/Library/Developer/CommandLineTools/`	CLI tools (headers, compilers)
`~/Library/Developer/`	User developer data
`~/Library/Developer/Xcode/`	Xcode user data
`~/Library/Developer/Xcode/DerivedData/`	Build products
`/Applications/Xcode.app/Contents/Developer/Platforms/`	SDKs

SDK and Header Locations

# Find active developer directory
$ xcode-select -p
/Library/Developer/CommandLineTools

# Find SDK path
$ xcrun --show-sdk-path
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk

# SDK locations
/Library/Developer/CommandLineTools/SDKs/
├── MacOSX.sdk -> MacOSX14.sdk
├── MacOSX14.sdk/
│   └── usr/include/        # System headers
└── MacOSX13.sdk/

Homebrew

Location (Apple Silicon)	Location (Intel)	Contents
`/opt/homebrew/`	`/usr/local/`	Homebrew prefix
`/opt/homebrew/bin/`	`/usr/local/bin/`	Executable symlinks
`/opt/homebrew/Cellar/`	`/usr/local/Cellar/`	Installed packages
`/opt/homebrew/Caskroom/`	`/usr/local/Caskroom/`	Installed casks
`/opt/homebrew/etc/`	`/usr/local/etc/`	Configuration files
`/opt/homebrew/var/`	`/usr/local/var/`	Variable data

# Find Homebrew prefix
$ brew --prefix
/opt/homebrew

# Find package location
$ brew --prefix postgresql
/opt/homebrew/opt/postgresql

# Find config file location
$ brew --prefix/etc/nginx/nginx.conf

Language Version Managers

Tool	Configuration	Versions Location
pyenv	`~/.pyenv/`	`~/.pyenv/versions/`
rbenv	`~/.rbenv/`	`~/.rbenv/versions/`
nvm	`~/.nvm/`	`~/.nvm/versions/`
nodenv	`~/.nodenv/`	`~/.nodenv/versions/`
rustup	`~/.rustup/`	`~/.rustup/toolchains/`

Network Configuration

DNS

Location	Purpose
`/etc/resolv.conf`	DNS resolver configuration (often managed by macOS)
`/etc/hosts`	Static hostname mappings
`/Library/Preferences/SystemConfiguration/preferences.plist`	Network service configuration

# View DNS configuration
$ scutil --dns

# View network configuration
$ cat /Library/Preferences/SystemConfiguration/preferences.plist | plutil -convert xml1 -o - -

SSH

Location	Purpose
`~/.ssh/config`	User SSH client configuration
`~/.ssh/known_hosts`	Known host keys
`~/.ssh/authorized_keys`	Keys allowed to log in as you
`~/.ssh/id_rsa`, `~/.ssh/id_ed25519`	Private keys
`~/.ssh/id_rsa.pub`, `~/.ssh/id_ed25519.pub`	Public keys
`/etc/ssh/ssh_config`	System-wide SSH client config
`/etc/ssh/sshd_config`	SSH server configuration

Firewall

Location	Purpose
`/etc/pf.conf`	Packet Filter configuration
`/etc/pf.anchors/`	PF anchor rules
`/Library/Preferences/com.apple.alf.plist`	Application Layer Firewall settings

Security

Keychain

Location	Purpose
`~/Library/Keychains/login.keychain-db`	User login keychain
`/Library/Keychains/System.keychain`	System keychain
`/System/Library/Keychains/SystemRootCertificates.keychain`	Root certificates

TCC (Privacy) Database

Location	Purpose
`~/Library/Application Support/com.apple.TCC/TCC.db`	User privacy permissions
`/Library/Application Support/com.apple.TCC/TCC.db`	System privacy permissions

Gatekeeper

# Gatekeeper configuration
$ spctl --status
assessments enabled

# Security assessment policy
/var/db/SystemPolicy
/var/db/SystemPolicyConfiguration

Logs

Unified Logging

macOS uses a unified logging system. Logs are stored in a binary format:

Location	Purpose
`/var/db/diagnostics/`	Log data store
`/var/db/uuidtext/`	Log text data

# View recent logs
$ log show --last 1h

# Stream live logs
$ log stream

# Filter by process
$ log show --predicate 'process == "Safari"' --last 30m

# Filter by subsystem
$ log show --predicate 'subsystem == "com.apple.network"' --last 1h

Traditional Log Files

Location	Contents
`/var/log/system.log`	General system log (limited)
`/var/log/install.log`	Installation logs
`/var/log/wifi.log`	Wi-Fi diagnostics
`~/Library/Logs/`	User application logs
`/Library/Logs/`	System application logs
`/Library/Logs/DiagnosticReports/`	Crash reports
`~/Library/Logs/DiagnosticReports/`	User crash reports

Comparison: macOS vs Linux

Configuration File Locations

Purpose	macOS	Linux
Shell config	`~/.zshrc`	`~/.bashrc`, `~/.zshrc`
App preferences	`~/Library/Preferences/*.plist`	`~/.config/`, `~/.<app>`
App data	`~/Library/Application Support/`	`~/.local/share/`, `~/.<app>`
App cache	`~/Library/Caches/`	`~/.cache/`
System services	`/Library/LaunchDaemons/`	`/etc/systemd/system/`
User services	`~/Library/LaunchAgents/`	`~/.config/systemd/user/`
Fonts	`~/Library/Fonts/`, `/Library/Fonts/`	`~/.fonts/`, `/usr/share/fonts/`
Binaries	`/usr/local/bin/`, `/opt/homebrew/bin/`	`/usr/local/bin/`
Service config	Embedded in .plist	`/etc/<service>/`

Service Configuration

Linux (systemd):

/etc/systemd/system/myservice.service
/etc/myservice/config.conf          # Separate config file

macOS (launchd):

/Library/LaunchDaemons/com.example.myservice.plist
# Configuration often embedded in plist or in:
/Library/Application Support/MyService/config.conf

Path Differences

Purpose	macOS	Linux
Package manager prefix	`/opt/homebrew/` (ARM), `/usr/local/` (Intel)	Varies by distro
System binaries	`/bin/`, `/sbin/`, `/usr/bin/`	Same (or merged `/usr/bin/`)
Temp files	`/private/tmp/` (`/tmp/` symlink)	`/tmp/`
Variable data	`/private/var/` (`/var/` symlink)	`/var/`
Optional software	`/opt/`	`/opt/`
Mounts	`/Volumes/`	`/mnt/`, `/media/`

Finding Configuration Files

Using Spotlight

# Find all plist files
$ mdfind -name ".plist"

# Find config files in Library
$ mdfind -onlyin ~/Library "kMDItemFSName == '*.conf'"

# Find preference files for an app
$ mdfind "kMDItemContentType == 'com.apple.property-list'" | grep -i appname

Using find

# Find all hidden config files in home
$ find ~ -maxdepth 1 -name ".*" -type f

# Find all plist files in Library
$ find ~/Library -name "*.plist" 2>/dev/null

# Find all configuration directories
$ find ~ -maxdepth 2 -type d -name ".*" 2>/dev/null

Common Locations to Check

When troubleshooting an application, check these locations:

# Preferences
~/Library/Preferences/com.<company>.<app>.plist
~/Library/Preferences/<app>.plist

# Application Support
~/Library/Application Support/<App Name>/

# Caches
~/Library/Caches/<App Name>/
~/Library/Caches/com.<company>.<app>/

# Containers (sandboxed apps)
~/Library/Containers/<bundle-id>/

# Logs
~/Library/Logs/<App Name>/

# Launch Agents (if app has background services)
~/Library/LaunchAgents/com.<company>.<app>.plist

Quick Reference: Key Locations

User Configuration

~/.zshrc                              # Zsh configuration
~/.ssh/config                         # SSH client configuration
~/.gitconfig                          # Git configuration
~/Library/Preferences/                # Application preferences (plist)
~/Library/Application Support/        # Application data
~/Library/LaunchAgents/               # User launch agents

System Configuration

/etc/hosts                            # Host name mappings
/etc/paths                            # System PATH
/etc/shells                           # Valid login shells
/etc/ssh/                             # SSH server configuration
/Library/LaunchDaemons/               # System daemons
/Library/Preferences/                 # System-wide app preferences

Development

/Library/Developer/CommandLineTools/  # Xcode CLI tools
/opt/homebrew/                        # Homebrew (Apple Silicon)
/usr/local/                           # Homebrew (Intel) / local software
~/.pyenv/, ~/.rbenv/, ~/.nvm/         # Language version managers

Homebrew Services

/opt/homebrew/etc/                    # Configuration files
/opt/homebrew/var/                    # Data files
/opt/homebrew/var/log/                # Log files
~/Library/LaunchAgents/homebrew.*     # Service plists

Keyboard shortcuts

macOS and Unix: The Complete Guide