pty.swift

import Foundation
import Darwin

class A: NSObject {
    var task = Process()

    var slaveFile: FileHandle?
    var masterFile: FileHandle?

    override init() {
        let masterFD = posix_openpt(O_RDWR)

        grantpt(masterFD)
        unlockpt(masterFD)

        self.masterFile = FileHandle.init(fileDescriptor: masterFD)

        let slavePath = String.init(cString: ptsname(masterFD))

        self.slaveFile = FileHandle.init(forUpdatingAtPath: slavePath)

        self.task.executableURL = URL(fileURLWithPath: "/bin/bash")
        self.task.arguments = ["-i"]

        self.task.standardOutput = slaveFile
        self.task.standardInput = slaveFile
        self.task.standardError = slaveFile
    }
    func run() {
        DispatchQueue.global(qos: .userInitiated).async { [weak self] in
            guard let self = self else {
                return
            }
            do {
                try self.task.run()
            } catch {
                fatalError("failed to start task: \(error)")
            }
        }

        let data1 = self.masterFile!.availableData
        let output1 = String(data: data1, encoding: String.Encoding.utf8)!

        print("Output: \(output1)")

        self.masterFile!.write("echo $HOME\u{0d}".data(using: String.Encoding.utf8)!)

        sleep(2)

        let data2 = self.masterFile!.availableData
        let output2 = String(data: data2, encoding: String.Encoding.utf8)!

        print("Output: \(output2)")
    }
}

let a = A()
a.run()