Launchctl

launchctl is the command-line interface for controlling launchd, macOS's service management framework. launchd is responsible for starting, stopping, and supervising daemons and agents, and for orchestrating periodic or event-driven tasks as defined by plist files.

Plist files configure each job. They describe the program to run, its arguments, environment, and behavior flags such as RunAtLoad, KeepAlive, StartInterval, and UserName. Plists are stored under /Library/LaunchDaemons, /Library/LaunchAgents, /System/Library/LaunchDaemons, /System/Library/LaunchAgents, and per-user plists under ~/Library/LaunchAgents. launchd loads these definitions and runs the corresponding processes, maintaining them according to the specified policy.

Usage: launchctl can list loaded jobs, load or unload a plist, and start or stop a specific job. On older macOS versions, load and unload were common; on newer releases the command set emphasizes bootstrap, kickstart, enable, disable, and print alongside list. Root privileges are typically required for system-domain operations.

Administrative considerations: Misconfigured plists can prevent login or boot in severe cases. Changes are best tested carefully, and removal of a faulty plist should be performed with care.