.swift

// $ ps -c -Ao pid,comm,pcpu -r | tail -n +2 | head -n 5
//  2333 installd          61.8
//  2671 iTerm2            17.3
//  2334 storedownloadd     4.1
//   203 WindowServer       2.8
//  5243 Activity Monitor   2.7
func getTopCpuProcs() {
    let ps = Process()
    ps.launchPath = "/usr/bin/env"
    ps.arguments = ["ps", "-c", "-Ao", "pid,comm,pcpu,time", "-r"]
    let psOut = Pipe()
    ps.standardOutput = psOut
    
    let tail = Process()
    tail.launchPath = "/usr/bin/env"
    tail.arguments = ["tail", "-n", "+2"]
    tail.standardInput = psOut
    let tailOut = Pipe()
    tail.standardOutput = tailOut
    
    let head = Process()
    head.launchPath = "/usr/bin/env"
    head.arguments = ["head", "-n", "5"]
    head.standardInput = tailOut
    let headOut = Pipe()
    head.standardOutput = headOut
    
    // Trim leading whitespace
    let sed1 = Process()
    sed1.launchPath = "/usr/bin/env"
    sed1.arguments = ["sed", #"s/^ *//g"#]
    sed1.standardInput = headOut
    let sed1Out = Pipe()
    sed1.standardOutput = sed1Out
    
    // Smush consecutive spaces into commas
    let sed2 = Process()
    sed2.launchPath = "/usr/bin/env"
    sed2.arguments = ["sed", #"s/ \{1,\}/,/g"#]
    sed2.standardInput = sed1Out
    let sed2Out = Pipe()
    sed2.standardOutput = sed2Out
    
    ps.launch()
    tail.launch()
    head.launch()
    sed1.launch()
    sed2.launch()
    sed2.waitUntilExit()
    
    let data = sed2Out.fileHandleForReading.readDataToEndOfFile()
    let output = NSString(data: data, encoding: String.Encoding.utf8.rawValue)
    
    if output!.length == 0 {
        print("no output")
        return
    }
    
    // Parse it
}