swift - Running A Shell Script With Swift in Cocoa

Question

I'm working on a Mac desktop app and trying to run a shell script. I'm getting hung up on setting a launch path for the task. Here's the code:

    let path = fileURL.deletingLastPathComponent().relativePath

    //set new filename
    let strNewFileName = fileURL.deletingPathExtension().lastPathComponent.appending(".html")

    let newPath = path + "/" + strNewFileName

    //create script
    var strScript = "pandoc -s -o "
    strScript.append(newPath)
    strScript.append(" ")
    strScript.append(fileURL.absoluteString)

    //set storage path
    let documentsPath = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0]
    var documentPath:URL = URL(string: documentsPath)!
    documentPath.appendPathComponent("pandoc.sh")

    var myURLComponents = URLComponents()
    myURLComponents.scheme = "file"
    myURLComponents.path = documentPath.absoluteString


    do {
        //write file
        try strScript.write(to: myURLComponents.url!, atomically: true, encoding: String.Encoding.utf8)

        //run script
        let myTask = Process()

        myTask.launchPath = "/usr/bin/env"
        myTask.arguments = [strScript]

        let myPipe = Pipe()
        myTask.standardOutput = myPipe

        myTask.launch()

        let data = myPipe.fileHandleForReading.readDataToEndOfFile()
        let output = NSString(data: data, encoding: String.Encoding.utf8.rawValue)

        print(output!)



    } catch {
        print(error.localizedDescription)
    }

This throws a no such file error:

env: pandoc -s -o /Users/stevensuranie/Desktop/MarkdownFiles/targeting-params-ios.html file:///Users/stevensuranie/Desktop/MarkdownFiles/targeting-params-ios.md: No such file or directory

Any help would be appreciated.

标签： swiftshellcocoa

Answer 1

This line cannot work

var documentPath:URL = URL(string: documentsPath)!

URL(string is for URL strings including the scheme (file:// or https://), for file system paths you must use URL(fileURLWithPath.

However if you use the URL related API of FileManager you can avoid the init method at all.
A similar issue is absoluteString, never call it on a file system URL, use always path.

A second fatal issue is that each shell argument must be an item in the arguments array and the executable must be specified with the full path

//create script
let scriptArguments = ["/path/to/pandoc", "-s", "-o", newPath, fileURL.path]

//set storage path
let documentsURL = try! FileManager.default.url(for: .documentDirectory, in: .userDomainMask, appropriateFor: nil, create: false)
let scriptURL = documentsURL.appendingPathComponent("pandoc.sh")

The following lines are redundant

var myURLComponents = URLComponents()
myURLComponents.scheme = "file"
myURLComponents.path = documentPath.absoluteString

The write the string to scriptURL

do {
    //write file
    try strScript.write(to: scriptURL, atomically: true, encoding: .utf8)
...

    myTask.arguments = scriptArguments

---

And finally don't use NS... classes in Swift

let output = NSString(data: data, encoding: String.Encoding.utf8.rawValue)

Use the native equivalent

let output = String(data: data, encoding: .utf8)