run bash command

shell.swift

import Foundation
#if os(OSX)
  func bash(command: String) -> String? {
    let task = Process()
    task.launchPath = "/bin/bash"
    task.arguments = ["-c", command]
    let o = Pipe()
    task.standardOutput = o
    task.launch()
    task.waitUntilExit()
    let data = o.fileHandleForReading.readDataToEndOfFile()
    return String(data: data, encoding: .utf8)
  }
#else
  import Glibc
  func bash(command: String) -> String? {
    guard let f = popen(command, "r") else { return nil }
    defer { pclose(f) }
    var data = Data()
    let szbuf = 8192
    var size = 0
    let buffer = UnsafeMutablePointer<UInt8>.allocate(capacity: szbuf)
    defer { buffer.deallocate(capacity: szbuf) }
    repeat {
      memset(buffer, 0, szbuf)
      size = fread(buffer, 1, szbuf, f)
      if size > 0 {
        let buf = UnsafeBufferPointer<UInt8>(start: buffer, count: size)
        data += Array(buf)
      }
    } while (size > 0)
    return String(data: data, encoding: .utf8)
  }
#endif

let script = """
cat /etc/hosts | grep 127
"""
if let result = bash(command: script) {
  print(result)
}