Problems encountered

When developing a Mac App, you need to execute a shell script. Below are several ways to implement this requirement and a discussion of related issues

  • useNSTask(called Process in Swfit)performshell
  • useNSAppleScriptTo borrowappleScriptperformdo shell script echo "echo test"completeshellScript execution
    • NSUserAppleScriptProvides implementationAppleScriptMultithreading scheme of the

There are several other apis that can execute shells. Since previous development only covered the three apis provided above, unfamiliar apis will not be discussed here

The following are discussions and examples of the three apis

NSTask

A subProcess is generated when the script is executed, which is represented by support for multithreaded invocation (multiple shell scripts can be executed asynchronously and concurrently). Unlike appleScript, NSTask does not trigger an authorization popup for the user to enter a native password when executing a shell script requiring authorization (SUdo).

Pass in the path of a shell script.

Note: After manually creating a shell script on Mac, you need to execute the chmod +x shell script path to authorize the script. Otherwise, the script cannot be executed

typealias RunShellScriptResult = (_ executeResult: String) - > ()private func runShellScript(_path: String? , onComplete: @escaping RunShellScriptResult) {
    guard let path = path, FileManager.default.fileExists(atPath: path) else {
        onComplete("Path does not exist!")
        return
    }
    
    let task = Process()
    task.launchPath = path
    task.arguments = [""]
    let outPipe = Pipe()
    task.standardOutput = outPipe
    task.launch()
    let fileHandle = outPipe.fileHandleForReading
    let data = fileHandle.readDataToEndOfFile()
    let string = String.init(data: data, encoding: .utf8)
    task.waitUntilExit()
    
    // Get the run result
    task.terminationHandler = { task in
        print("Perform\(path)")
        onComplete(string ?? "")}}Copy the code

Pipe is used to accept the result of executing a shell script.

NSAppleScript

AppleScript can do a lot of things on its own. We can open the script editor on the Mac and edit our own Apple scripts. I will not elaborate on this here. We use it to execute shell scripts that require sudo authorization, prompting for authorization.

Unlike NSTask/Process, the argument passed is a string of the contents of the shell script.

Do shell script “echo Command “with Administrator PRIVILEGES will add the authorization pop-up prompt.

/// Run the script command /// /// -parameters: /// -command: command line content /// -needauthorize: Whether sudo authorization is required when executing the script /// - Returns: Private func runCommand(_ command: String, needAuthorize: Bool) -> (isSuccess: Bool, executeResult: String?) { let scriptWithAuthorization = """ do shell script "\(command)" with administrator privileges """ let scriptWithoutAuthorization = """ do shell script "\(command)" """ let script = needAuthorize ? scriptWithAuthorization : scriptWithoutAuthorization let appleScript = NSAppleScript(source: script) var error: NSDictionary? = nil let result = appleScript! .executeAndreTurnerror (&error) if let error = error {print(" run \n\(command)\n :") print(error) return (false, nil) } return (true, result.stringValue) }Copy the code

Problem solved by NSUserAppleScript

NSAppleScript solves the authorization problem, but it executes on the main thread. In other words, he does not support multithreaded execution. If we need to execute several shell scripts at the same time, and the previous shell is a time-consuming operation like ping, you can just wait.

I took this quote from a reference article written by Meow God

One of the nice things in NSUserAppleScriptTask is the callback handling at the end. Scripts are executed asynchronously, so your user interface is not locked by a (long) script. Be careful what you do in the closing callback, because it doesn’t run on the main thread, so you can’t make updates to your user interface there.


do {
    // The URL here is the path of the shell script
    let task = try NSUserAppleScriptTask.init(url: url) 
    task.execute(withAppleEvent: nil) { (result, error) in
        varmessage = result? .stringValue ??""
        // Error. DebugDescription is also part of the execution result. It is used when a timeout or the execution shell itself returns an error and we need to print the content.
        
        message = message.count= =0 ? error.debugDescription : message
    }
} catch {
    // Execution related errors
}
Copy the code