Subprocess

Subprocess is a Swift library for macOS providing interfaces for both synchronous and asynchronous process execution. SubprocessMocks can be used in unit tests for quick and highly customizable mocking and verification of Subprocess usage.

• Usage
  • Shell
    • Input - Data, Text, File
    • Output - Data, Text, JSON, Decodable JSON object, Property list, Decodable property list object
  • Subprocess
• Installation
  • SwiftPM
  • Cocoapods
  • Carthage

Full Documentation

Usage

Shell Class

The Shell class can be used for synchronous command execution.

Command Input

Input for data

let inputData: Data = ...
let data = try Shell(["/usr/bin/grep", "Hello"]).exec(input: .data(inputData))

Input for text

let data = try Shell(["/usr/bin/grep", "Hello"]).exec(input: .text("Hello world"))

Input for file URL

let url = URL(fileURLWithPath: "/path/to/input/file")
let data = try Shell(["/usr/bin/grep", "foo"]).exec(input: .file(url: url))

Input for file path

let data = try Shell(["/usr/bin/grep", "foo"]).exec(input: .file(path: "/path/to/input/file"))

Command Output

Output as Data

let data = try Shell(["/usr/bin/sw_vers"]).exec()

Output as String

let text = try Shell(["/usr/bin/sw_vers"]).exec(encoding: .utf8)

Output as JSON (Array or Dictionary)

let command = ["/usr/bin/log", "show", "--style", "json", "--last", "5m"]
let logs: [[String: Any]] = try Shell(command).execJSON())

Output as decodable object from JSON

struct LogMessage: Codable {
    var subsystem: String
    var category: String
    var machTimestamp: UInt64
}
let command = ["/usr/bin/log", "show", "--style", "json", "--last", "5m"]
let logs: [LogMessage] = try Shell(command).exec(decoder: JSONDecoder())

Output as Property List (Array or Dictionary)

let command = ["/bin/cat", "/System/Library/CoreServices/SystemVersion.plist"]
let dictionary: [String: Any] = try Shell(command).execPropertyList())

Output as decodable object from Property List

struct SystemVersion: Codable {
    enum CodingKeys: String, CodingKey {
        case version = "ProductVersion"
    }
    var version: String
}
let command = ["/bin/cat", "/System/Library/CoreServices/SystemVersion.plist"]
let result: SystemVersion = try Shell(command).exec(decoder: PropertyListDecoder())

Output mapped to other type

let enabled = try Shell(["csrutil", "status"]).exec(encoding: .utf8) { _, txt in txt.contains("enabled") }

Output options

let command: [String] = ...
let errorText = try Shell(command).exec(options: .stderr, encoding: .utf8)
let outputText = try Shell(command).exec(options: .stdout, encoding: .utf8)
let combinedData = try Shell(command).exec(options: .combined)

Subprocess Class

The Subprocess class can be used for asynchronous command execution.

Handling output as it is read

let command: [String] = ...
let process = Subprocess(command)

// The outputHandler and errorHandler are invoked serially
try process.launch(outputHandler: { data in
    // Handle new data read from stdout
}, errorHandler: { data in
    // Handle new data read from stderr
}, terminationHandler: { process in
    // Handle process termination, all scheduled calls to
    // the outputHandler and errorHandler are guaranteed to
    // have completed.
})

Handling output on termination

let command: [String] = ...
let process = Subprocess(command)

try process.launch { (process, outputData, errorData) in
    if process.exitCode == 0 {
        // Do something with output data
    } else {
        // Handle failure
    }
}

Installation

SwiftPM

dependencies: [
	.package(url: "https://github.com/jamf/Subprocess.git", from: "1.0.0")
]

Cocoapods

pod 'Subprocess'

Carthage

github 'jamf/Subprocess'