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.

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)
}

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.

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.

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.

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.

Encapsulates the inetdCompatibility wait key.

Encapsulates the SoftResourceLimits and HardResourceLimits keys:

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

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

• 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.