(SOLVED) Minimal program to illustrate a possible misunderstanding of what os.exec() can and cannot do with external programs' output.

illustrated_exec.go

package main

import (
	"fmt"
	"log"
	"os"
	"os/exec"
)

type MyWriter struct{}

func (w *MyWriter) Write(p []byte) (n int, err error) {
	fmt.Fprintf(os.Stdout, "MyWriter: %v", string(p))
	n = len(p)
	return
}

func main() {
	// sleepecho is a simple, executable bash script, with contents:

	//     #!/bin/bash
	//     sleep 1 && echo -n . && sleep 1 && echo -n . && sleep 1 && echo -n . && sleep 1 && echo .

	myCommand := exec.Command("./sleepecho")

	myCommand.Stdout = &MyWriter{}

	if err := myCommand.Start(); err != nil {
		log.Fatal(err)
	}

	defer func() {
		if err := myCommand.Wait(); err != nil {
			log.Fatal(err)
		}
	}()
}