simple solution to solve wanting a variable N number of receivers to an io.Writer in Golang

main.go

package main

import (
	"bufio"
	"fmt"
	"io"
	"log"
	"os/exec"
	"sync"
	"time"
)

type Job struct {
	Command  string
	mutex    sync.Mutex
	monitors map[int]io.Writer
}

func (j *Job) AddMonitor(id int, writer io.Writer) {
	j.mutex.Lock()
	j.monitors[id] = writer
	j.mutex.Unlock()
}

func (j *Job) RemoveMonitor(id int) {
	j.mutex.Lock()
	delete(j.monitors, id)
	j.mutex.Unlock()
}

func (j *Job) Run() {
	reader, writer := io.Pipe()
	bufferedReader := bufio.NewReader(reader)

	osCmd := exec.Command("/bin/bash", "-c", j.Command)
	osCmd.Stdout = writer
	var wg sync.WaitGroup
	wg.Add(1)
	go func() {
		defer wg.Done()
		if err := osCmd.Run(); err != nil {
			log.Fatalln(err)
		}
		writer.Close()
	}()

	buf := make([]byte, 1024)
	var n int
	var err error
	for {
		n, err = bufferedReader.Read(buf)
		if err != nil {
			if err == io.EOF {
				break
			}
			fmt.Println("Error reading from buffer:", err)
			return
		}
		j.mutex.Lock()

		for _, monitor := range j.monitors {
			if _, err = monitor.Write(buf[:n]); err != nil {
				log.Fatalln("Could not send to writer")
			}
		}
		j.mutex.Unlock()
	}

		// Wait for the command to complete
		wg.Wait()
}

func CreateMonitor(index int) io.Writer {
	reader, writer := io.Pipe()
	bufferedReader := bufio.NewReader(reader)

	go func() {
		for {
			buf := make([]byte, 1024)
			var n int
			var err error
			n, err = bufferedReader.Read(buf)
			if err != nil {
				if err == io.EOF {
					break
				}
				fmt.Println("Error reading from buffer:", err)
				return
			}
			fmt.Println(fmt.Sprintf("Monitor %d read: %s", index, buf[:n]))
		}
	}()
	return writer
}

func main() {

	j := &Job{
		Command: "while true; do echo 'data'; sleep 1; done",
		monitors: map[int]io.Writer{},
	}
	go j.Run()

	for i := 0; i < 5; i++ {
		j.AddMonitor(i,CreateMonitor(i))
	}

	for i := 4; i >= 0; i-- {
		time.Sleep(5*time.Second)
		fmt.Println("removing monitor: ",i)
		j.RemoveMonitor(i)
	}

}