LaunchAgent

LaunchAgent provides an easy way to pragmatically create and maintain launchd agents and daemons without needing to manually build Property Lists.

Take a look at the full documentation.

LaunchAgent

A LaunchAgent can be created with either an array of program arguments:

LaunchAgent(label: "local.PythonServer", program: ["python", "-m", "SimpleHTTPServer", "8000"])

or with variadic parameters:

LaunchAgent(label: "local.PythonServer", program: "python", "-m", "SimpleHTTPServer", "8000")

The agent can also be created with only a label, but will be invalid if loaded:

LaunchAgent(label: "local.PythonServer")

When creating a new agent it needs to be written to disk:

let agent = LaunchAgent(label: "local.PythonServer", program: "python", "-m", "SimpleHTTPServer", "8000")

do {
    try LaunchControl.shared.write(agent)
    try agent.load()
    agent.start()
} catch {
    print("Unexpected error:" error)
}

Using LaunchControl to read and write LaunchAgents

The LaunchControl class can read agents from and write agents to ~/Library/LaunchAgents. When using either method the url of the loaded agent will be set.

Controlling LaunchAgents

LaunchAgent has load(), unload(), start(), stop(), and status() methods which do what they say on the tin.

Load & unload require the agent’s URL parameter to be set, or launchctl won’t be able to locate them. Start, stop, and status are called based on the label.

Supported Keys

LaunchAgent does not currently support all keys, and there are some caveats to some keys it does support.

Most parameters in the LaunchAgent class are optional, and setting nil will remove the key from the encoded plist. Some keys use their own type to encapsulate a complex dictionary value.

Basic Config

Key Name	Key type	Supported	Notes
Label	String	true
Disabled	String	true
Program	String	true
ProgramArguments	[String]	true
EnableGlobbing	Bool	true	deprecated in macOS

Program

Key Name	Key type	Supported	Notes
workingDirectory	String	true
standardInPath	String	true
standardOutPath	String	true
standardErrorPath	String	true
environmentVariables	[String: String]	true

Run Conditions

Key Name	Key type	Supported	Notes
runAtLoad	Bool	true
startInterval	Int	true
startCalendarInterval	StartCalendarInterval	true
startOnMount	Bool	true
onDemand	Bool	true
keepAlive	Bool	true
watchPaths	[String]	true
queueDirectories	[String]	true

Security

Key Name	Key type	Supported	Notes
umask	Int	true	Use FilePermissions.umaskDecimal to get a valid value
sessionCreate	Bool	true
groupName	String	true
userName	String	true
initGroups	Bool	true
rootDirectory	String	true

Run Constraints

Key Name	Key type	Supported	Notes
launchOnlyOnce	Bool	true
limitLoadToSessionType	[String]	true	Always encodes as an array
limitLoadToHosts	[String]	true
limitLoadFromHosts	[String]	true

Control

Key Name	Key type	Supported	Notes
AbandonProcessGroup	Bool	true
EnablePressuredExit	Bool	true
EnableTransactions	Bool	true
ExitTimeOut	Int	true
inetdCompatibility	inetdCompatibility	true
HardResourceLimits	ResourceLimits	true
SoftResourceLimits	ResourceLimits	true
TimeOut	Int	true
ThrottleInterval	Int	true

IPC

Key Name	Key type	Supported	Notes
MachServices	[String: MachService]	true
Sockets		false

Debug

Key Name	Key type	Supported	Notes
Debug	Bool	true	Deprecated
WaitForDebugger	Bool	true

Performance

Key Name	Key type	Supported	Notes
LegacyTimers	Bool	true
LowPriorityIO	Bool	true
LowPriorityBackgroundIO	Bool	true
Nice	Int	true
ProcessType	ProcessType enum	true

Custom Key Classes

StartCalendarInterval

The StartCalendarInterval encapsulates the dictionary for setting calendar-based job intervals. By default all values are set to nil, meaning the job will run on any occurrence of that value.

The Month and Weekday keys are represented by enums for each month and week, respectively. Day, Hour, and Minute values are simply integers. They are checked for validity in their respective time ranges, and will be set to the minimum or maximum value depending on which way they were out of bounds.

inetdCompatibility

Encapsulates the inetdCompatibility wait key.

ResourceLimits

Encapsulates the SoftResourceLimits and HardResourceLimits keys:

• cpu
• core
• data
• fileSize
• memoryLock
• numberOfFiles
• numberOfProcesses
• residentSetSize
• stack

FilePermissions

Individual permission Unix bits for read, write, and execute.

Unix Permissions

• Read: 4
• Write: 2
• Execute: 1

In addition you can get the umask value.

When setting permissions for a LaunchAgent use .umaskDecimal to get the value. If you’re reading a LaunchAgent FilePermissions(umask:) will read in the decimal so the permissions can be updated.