launchd — The macOS Process Manager

What launchd is

launchd is PID 1 on macOS. It combines the roles of init, systemd, cron, inetd, and xinetd into a single process. Understanding its architecture is necessary for understanding Safe Mode and for managing background processes.

Domains

launchd organizes services into domains, which are analogous to systemd scopes:

Domain	Who it serves	When it starts	systemd analogy
system	The entire machine	Boot	system units
user/<uid>	A specific user	User login	user units
gui/<uid>	A user’s GUI session	After WindowServer starts	session scope
login/<asid>	A specific login session	Per-login	PAM session scope

Service types

LaunchDaemons — run in the system domain, as root (or a specified user), no GUI session required. They start at boot and run continuously. Configuration plists live in:

• /System/Library/LaunchDaemons/ — Apple’s own daemons (on SSV, read-only)
• /Library/LaunchDaemons/ — third-party daemons (writable, Data volume)

LaunchAgents — run in the user or gui domain, as the logged-in user. They require a user session. Configuration plists live in:

• /System/Library/LaunchAgents/ — Apple agents (SSV, read-only)
• /Library/LaunchAgents/ — machine-wide third-party agents
• ~/Library/LaunchAgents/ — per-user third-party agents

Key launchctl commands

# List everything running in the system domain
sudo launchctl print system
 
# List everything in your user domain
launchctl print user/$(id -u)
 
# Stop a daemon temporarily (it will restart at next boot unless disabled)
sudo launchctl stop com.example.daemon
 
# Disable a daemon permanently (survives reboots)
sudo launchctl disable system/com.example.daemon
 
# Unload a specific plist (like systemctl stop + disable for one unit)
sudo launchctl bootout system /Library/LaunchDaemons/com.example.plist
 
# Load it back
sudo launchctl bootstrap system /Library/LaunchDaemons/com.example.plist

The Apple vs third-party distinction

launchd distinguishes Apple services from third-party services purely by filesystem path. Services in /System/Library/ are on the SSV (read-only, sealed, Apple-signed). Services in /Library/ or ~/Library/ are on the writable Data volume.

This distinction matters in Safe Mode, where all third-party services are skipped.

See also

• Safe Mode — what Safe Mode skips in launchd terms
• Recovery Mode — a completely different boot environment