在Go中运行Python命令

Question

I am trying following code:

package main
import ("fmt";  "log"; "os/exec")
func main() {
    cmd := exec.Command("/usr/bin/python3.5",  "-c",
        "import easygui as eg; print('Hello world'); eg.msgbox(msg='Hi there'); print('from Golang')")
    out, err := cmd.CombinedOutput()
    if err != nil {     log.Fatal(err)  }
    fmt.Printf(string(out)) }

I am trying it to print on terminal first, then show a gui messagebox, then again print on terminal.

However, it first shows a message box, then does both print statements.

How can this be solved?

Answer 1

Your program runs cmd.CombinedOutput(), which launches the Python script (as a side effect displaying the message box) and collects its stdout into a variable; then does a single fmt.Printf to print out the program's output. That leads to the sequencing you're seeing.

If you call cmd.StdoutPipe() then you will get an io.Reader that has the script's stdout instead. It's your responsibility to read from the pipe and copy to your own process's stdout; the os/exec documentation has an example. You need to cmd.Start(), then read everything from the pipe, then cmd.Wait() to clean up after yourself.

You may also be able to directly assign cmd.Stdout = os.Stdout, then cmd.Run(). In this case you won't be able to see the output within your program, but you also won't have to copy it around.