How do I run an terminal command in a swift script

Question

I want to replace my CI bash scripts with swift. I can't figure out how to invoke normal terminal command such as ls or xcodebuild

#!/usr/bin/env xcrun swift

import Foundation // Works
println("Test") // Works
ls // Fails
xcodebuild -workspace myApp.xcworkspace // Fails

---

$ ./script.swift
./script.swift:5:1: error: use of unresolved identifier 'ls'
ls // Fails
^
... etc ....

Answer 1

If you don't use command outputs in Swift code, following would be sufficient:

#!/usr/bin/env swift

import Foundation

@discardableResult
func shell(_ args: String...) -> Int32 {
    let task = Process()
    task.launchPath = "/usr/bin/env"
    task.arguments = args
    task.launch()
    task.waitUntilExit()
    return task.terminationStatus
}

shell("ls")
shell("xcodebuild", "-workspace", "myApp.xcworkspace")

Updated: for Swift3/Xcode8

Answer 2

Mixing rintaro and Legoless's answers for Swift 3

@discardableResult
func shell(_ args: String...) -> String {
    let task = Process()
    task.launchPath = "/usr/bin/env"
    task.arguments = args

    let pipe = Pipe()
    task.standardOutput = pipe

    task.launch()
    task.waitUntilExit()

    let data = pipe.fileHandleForReading.readDataToEndOfFile()

    guard let output: String = String(data: data, encoding: .utf8) else {
        return ""
    }
    return output
}

Answer 3

Full script based on Legoless's answer

#!/usr/bin/env xcrun swift

import Foundation

func printShell(launchPath: String, arguments: [AnyObject] = []) {
    let output = shell(launchPath, arguments:arguments)

    if (output != nil) {
        println(output!)
    }
}

func shell(launchPath: String, arguments: [AnyObject] = []) -> String? {

    let task = NSTask()
    task.launchPath = launchPath
    task.arguments = arguments

    let pipe = NSPipe()
    task.standardOutput = pipe
    task.launch()

    let data = pipe.fileHandleForReading.readDataToEndOfFile()
    let output: String? = NSString(data: data, encoding: NSUTF8StringEncoding)

    return output
}

// > ls
// > ls -a -g
printShell("/bin/ls")
printShell("/bin/ls", arguments:["-a", "-g"])

Answer 4

Updating for Swift 4.0 (dealing with changes to String)

func shell(launchPath: String, arguments: [String]) -> String
{
    let task = Process()
    task.launchPath = launchPath
    task.arguments = arguments

    let pipe = Pipe()
    task.standardOutput = pipe
    task.launch()

    let data = pipe.fileHandleForReading.readDataToEndOfFile()
    let output = String(data: data, encoding: String.Encoding.utf8)!
    if output.count > 0 {
        //remove newline character.
        let lastIndex = output.index(before: output.endIndex)
        return String(output[output.startIndex ..< lastIndex])
    }
    return output
}

func bash(command: String, arguments: [String]) -> String {
    let whichPathForCommand = shell(launchPath: "/bin/bash", arguments: [ "-l", "-c", "which \(command)" ])
    return shell(launchPath: whichPathForCommand, arguments: arguments)
}

Answer 5

The problem here is that you cannot mix and match Bash and Swift. You already know how to run Swift script from command line, now you need to add the methods to execute Shell commands in Swift. In summary from PracticalSwift blog:

func shell(launchPath: String, arguments: [String]) -> String?
{
    let task = Process()
    task.launchPath = launchPath
    task.arguments = arguments

    let pipe = Pipe()
    task.standardOutput = pipe
    task.launch()

    let data = pipe.fileHandleForReading.readDataToEndOfFile()
    let output = String(data: data, encoding: String.Encoding.utf8)

    return output
}

The following Swift code will execute xcodebuild with arguments and then output the result.

shell("xcodebuild", ["-workspace", "myApp.xcworkspace"]);

As for searching the directory contents (which is what ls does in Bash), I suggest using NSFileManager and scanning the directory directly in Swift, instead of Bash output, which can be a pain to parse.

Answer 6

If you would like to use command line arguments "exactly" as you would in command line (without separating all the arguments), try the following.

(This answer improves off of LegoLess's answer and can be used in Swift 4 Xcode 9.3)

func shell(_ command: String) -> String {
    let task = Process()
    task.launchPath = "/bin/bash"
    task.arguments = ["-c", command]

    let pipe = Pipe()
    task.standardOutput = pipe
    task.launch()

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

    return output
}

// Example usage:
shell("ls -la")