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Run Terminal Scripts from your Mac app
// Script.swift
// Buildasaur
// Created by Honza Dvorsky on 12/05/15.
// Copyright (c) 2015 Honza Dvorsky. All rights reserved.
import Foundation
* Utility class for running terminal Scripts from your Mac app.
public class Script {
public typealias ScriptResponse = (terminationStatus: Int, standardOutput: String, standardError: String)
* Run a script by passing in a name of the script (e.g. if you use just 'git', it will first
* resolve by using the 'git' at path `which git`) or the full path (such as '/usr/bin/git').
* Optional arguments are passed in as an array of Strings and an optional environment dictionary
* as a map from String to String.
* Back you get a 'ScriptResponse', which is a tuple around the termination status and outputs (standard and error).
public class func run(name: String, arguments: [String] = [], environment: [String: String] = [:]) -> ScriptResponse {
//first resolve the name of the script to a path with `which`
let resolved = self.runResolved("/usr/bin/which", arguments: [name], environment: [:])
//which returns the path + \n, so strip the newline
var path = resolved.standardOutput.stripTrailingNewline()
//if resolving failed, just abort and propagate the failed run up
if (resolved.terminationStatus != 0) || (count(path) == 0) {
return resolved
//ok, we have a valid path, run the script
let result = self.runResolved(path, arguments: arguments, environment: environment)
return result
* An alternative to is Script.runInTemporaryScript, which first dumps the passed in script
* string into a temporary file, runs it and then deletes it. More useful for more complex script that involve
* piping data between multiple scripts etc. Might be slower than, however.
public class func runTemporaryScript(script: String) -> ScriptResponse {
var resp: ScriptResponse!
self.runInTemporaryScript(script, block: { (scriptPath, error) -> () in
resp ="/bin/bash", arguments: [scriptPath])
return resp
private class func runInTemporaryScript(script: String, block: (scriptPath: String, error: NSError?) -> ()) {
let uuid = NSUUID().UUIDString
let tempPath = NSTemporaryDirectory().stringByAppendingPathComponent(uuid)
var error: NSError?
//write the script to file
let success = script.writeToFile(tempPath, atomically: true, encoding: NSUTF8StringEncoding, error: &error)
block(scriptPath: tempPath, error: error)
//delete the temp script
NSFileManager.defaultManager().removeItemAtPath(tempPath, error: nil)
private class func runResolved(path: String, arguments: [String], environment: [String: String]) -> ScriptResponse {
let outputPipe = NSPipe()
let errorPipe = NSPipe()
let outputFile = outputPipe.fileHandleForReading
let errorFile = errorPipe.fileHandleForReading
let task = NSTask()
task.launchPath = path
task.arguments = arguments
var env = NSProcessInfo.processInfo().environment
for (let index, let keyValue) in enumerate(environment) {
env[keyValue.0] = keyValue.1
task.environment = env
task.standardOutput = outputPipe
task.standardError = errorPipe
let terminationStatus = Int(task.terminationStatus)
let output = self.stringFromFileAndClose(outputFile)
let error = self.stringFromFileAndClose(errorFile)
return (terminationStatus, output, error)
private class func stringFromFileAndClose(file: NSFileHandle) -> String {
let data = file.readDataToEndOfFile()
let output = NSString(data: data, encoding: NSUTF8StringEncoding) as String?
return output ?? ""
public extension String {
public func stripTrailingNewline() -> String {
var stripped = self
if stripped.hasSuffix("\n") {
return stripped
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