Redirecting stderr on windows

General Usage
3

Thank you very much for your advice. Your solution works great.
I’ve simplified the working example to launch the task only for the nescessary time:

function popen3(cmd::Cmd)
    pin = Base.Pipe()
    out = Base.Pipe()
    err = Base.Pipe()
    r = spawn(cmd, (pin, out, err))
    Base.close_pipe_sync(out.in)
    Base.close_pipe_sync(err.in)
    Base.close_pipe_sync(pin.out)
    Base.start_reading(out.out)
    Base.start_reading(err.out)
    return (pin.in, out.out, err.out, r)
end

pr = popen3(`c:\\windows\\system32\\ping 127.0.0.1 -t`)

function readresult(pr)
    results = [""]
    @sync begin            
        @async begin
            #global results            
            results[1] = ascii(String(readavailable(pr[2])))
        end
    end
    results[1]
end

Calling readresult gives the right output. Note, the results string must be =[“”]. If it is =“”, the example doesn’t work.

Please could somebody explain me, how to get any results from a task - specifically how the valiables get scoped with the @async block. The manual mentions that all variables are surrounded by a let x=x expressions.
So far my example only works with the string encapsulated ina an array to be a reference.
is there a preferred way to get results from the @async block other than via Arrays?

Thank you
Petr