package main
import (
	"os/exec"
	"log"
	"fmt"
)
func main() {
	out, err := exec.Command("bash", "-c", "gcloud auth application-default login").Output()
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("输出为：%s\n", out)
}

gcloud auth application-default login

Your browser has been opened to visit:
    https://accounts.google.com/o/oauth2/auth?redirect_uri=h***********************************

/*
out, err := exec.Command("bash", "-c", "gcloud auth application-default login").CombinedOutput()
if err != nil {
    log.Fatal(err)
}
fmt.Printf("输出为：%s\n", out)
*/
cmd := exec.Command("bash", "-c", "gcloud auth application-default login")
cmdReader, err := cmd.StderrPipe()
if err != nil {
    fmt.Fprintln(os.Stderr, "Error creating StdoutPipe for Cmd", err)
    os.Exit(1)
}
scanner := bufio.NewScanner(cmdReader)
go func() {
    for scanner.Scan() {
        fmt.Printf("输出 | %s\n", scanner.Text())
    }
}()
out, err := exec.Command("bash", "-c", "gcloud auth application-default login").Output()
if err != nil {
    log.Fatal(err)
}
fmt.Printf("输出为：%s\n", out)

cmd := exec.Command("bash", "-c", "gcloud auth application-default login")
stderr, err := cmd.StderrPipe()
if err != nil {
    log.Fatal(err)
}
// 启动命令
if err = cmd.Start(); err != nil {
    log.Fatal(err)
}
// 防止 main() 在 cmd 完成之前退出
defer cmd.Wait()
// 读取命令输出并发送到标准输出
// 根据需要替换 os.Stderr
go io.Copy(os.Stdout, stderr)
fmt.Println("Standby to read...")
fmt.Println()
这只是一种方法，你可以根据自己的需求进行实现。祝你好运！
<details>
<summary>英文:</summary>
Found it why your snippet doesn&#39;t work as expected.
Typically `CombinedOutput()` and `Output()` returns the result after completion of given command.
Here `gcloud` command didn&#39;t finish the execution, so we have to read it realtime. I have tested the below code snippet, it works.
    cmd := exec.Command(&quot;bash&quot;, &quot;-c&quot;, &quot;gcloud auth application-default login&quot;)
	stderr, err := cmd.StderrPipe()
	if err != nil {
		log.Fatal(err)
	}
	// Start command
	if err = cmd.Start(); err != nil {
		log.Fatal(err)
	}
	// prevent main() to exit before cmd completes
	defer cmd.Wait()
	// read cmd output and send it to stdout
	// repalce os.Stderr as per your need
	go io.Copy(os.Stdout, stderr)
	fmt.Println(&quot;Standby to read...&quot;)
	fmt.Println()
This is just an approach, implement yours. Good luck!
</details>
# 答案2
**得分**: 0
该消息被打印到标准错误流(stderr)，而不是标准输出流(stdout)。
<details>
<summary>英文:</summary>
That message is printed to stderr, not stdout.
</details>