Document how to run other tools on command line

[yonaskolb]

Document how to run other tools on command line

[Jeehut]

One way could be to include something like the following code in a beak.swift file:

typealias CommandResult = (outputLines: [String], errorLines: [String], exitCode: Int32)

@discardableResult
func run(_ command: String) -> CommandResult {
    let commandComponents = command.components(separatedBy: .whitespacesAndNewlines)

    let commandLineTask = Process()
    commandLineTask.launchPath = "/usr/bin/env"
    commandLineTask.arguments = commandComponents

    let outputPipe = Pipe()
    commandLineTask.standardOutput = outputPipe
    let errorPipe = Pipe()
    commandLineTask.standardError = errorPipe

    commandLineTask.launch()

    var errorLines: [String] = []
    let errorData = errorPipe.fileHandleForReading.readDataToEndOfFile()

    if var errorDataString = String(data: errorData, encoding: .utf8) {
        errorDataString = errorDataString.trimmingCharacters(in: .newlines)
        errorLines = errorDataString.components(separatedBy: .newlines)
    }

    var outputLines: [String] = []
    let outputData = outputPipe.fileHandleForReading.readDataToEndOfFile()

    if var outputDataString = String(data: outputData, encoding: .utf8) {
        outputDataString = outputDataString.trimmingCharacters(in: .newlines)
        outputLines = outputDataString.components(separatedBy: .newlines)
    }

    commandLineTask.waitUntilExit()
    let exitCode = commandLineTask.terminationStatus

    return (outputLines, errorLines, exitCode)
}

This enables the following lines:

run("ruby -v") // => (outputLines: ["ruby 2.5.1p57 (2018-03-29 revision 63029) [x86_64-darwin17]"], errorLines: [""], exitCode: 0)
run("ruby -v").outputLines // => ["ruby 2.5.1p57 (2018-03-29 revision 63029) [x86_64-darwin17]"]
run("ruby -v").errorLines // => [""]
run("ruby -v").exitCode // => 0

Alternatively one could point to tools like SwiftShell and ShellOut) which both support SPM and therefore Beak.