如何强制golang关闭打开的管道

Question

I have to process a long output of a script and find some data. This data most likely will be located at the almost very beginning of the output. After data found I do not need to process output anymore and can quit.

The issue that I cannot stop processing output because exec.Cmd does not have any function to close opened command.

Here are some simplified code (error handling was ommited):

func processOutput(r *bufio.Reader)(){
   for {
      line, _, err := r.ReadLine()
      if some_condition_meet {
         break
      }
      ......
   }
   return
}

func execExternalCommand(){
   cmdToExecute := "......"
   cmd := exec.Command("bash", "-c", cmdToExecute)
   output, _ := cmd.StdoutPipe()

   cmd.Start()
   r := bufio.NewReader(output)
   go processOutput(r)
   cmd.Wait()
   return
}  

What should I do at the end at processOutput function to stop cmd? Maybe there is another way how to solve it.

Thanks

Answer 1

As it stands, you can't do this from processOutput because all it receives is a bufio.Reader. You would need to pass the exec.Cmd to it for it to do anything with the forked process.

To kill the forked process, you can send it a signal, e.g.: cmd.Process.Kill() or cmd.Process.Signal(os.SIGINT). See documentation on exec.Cmd and os.Process.