问题

我想在Go中执行一个命令，并将其stdout和stderr合并为一个流。我写了这段代码，它只从stdout中读取，但我不知道如何将其与stderr合并：

package main

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

func runCommand() {
    var (
        err error
    )

    cmdName := "docker"
    cmdArgs := []string{"build", "--no-cache=true", "--force-rm=true", "."}

    cmd := exec.Command(cmdName, cmdArgs...)

    cmdReader, err := cmd.StdoutPipe()
    if err != nil {
        fmt.Fprintln(os.Stderr, "Error creating StdoutPipe for Cmd", err)
    }

    scanner := bufio.NewScanner(cmdReader)
    go func() {
        for scanner.Scan() {
            fmt.Printf("docker build out | %s\n", scanner.Text())
        }
    }()

    err = cmd.Start()
    if err != nil {
        fmt.Fprintln(os.Stderr, "Error starting Cmd", err)
    }

    err = cmd.Wait()
    if err != nil {
        fmt.Fprintln(os.Stderr, "Error waiting for Cmd", err)
    }
}

func main() {
    runCommand()
}

谢谢所有的回答！

<details>
<summary>英文:</summary>

I would like to execute a command in Go, and combining its stdout and stderr into one stream. I wrote this code, its read only from the stdout, but I don&#39;t know how to I combine it with the stderr:

    package main

    import (
        &quot;fmt&quot;
        &quot;os&quot;
        &quot;os/exec&quot;
        &quot;bufio&quot;
    )

    func runCommand() {
        var (
            err error
        )

        cmdName := &quot;docker&quot;
        cmdArgs := []string{&quot;build&quot;, &quot;--no-cache=true&quot;, &quot;--force-rm=true&quot;, &quot;.&quot;}

        cmd := exec.Command(cmdName, cmdArgs...)

        cmdReader, err := cmd.StdoutPipe()
        if err != nil {
            fmt.Fprintln(os.Stderr, &quot;Error creating StdoutPipe for Cmd&quot;, err)
        }

        scanner := bufio.NewScanner(cmdReader)
        go func() {
            for scanner.Scan() {
                fmt.Printf(&quot;docker build out | %s\n&quot;, scanner.Text())
            }
        }()

        err = cmd.Start()
        if err != nil {
            fmt.Fprintln(os.Stderr, &quot;Error starting Cmd&quot;, err)
        }

        err = cmd.Wait()
        if err != nil {
            fmt.Fprintln(os.Stderr, &quot;Error waiting for Cmd&quot;, err)
        }
    }

    func main() {
        runCommand()
    }

Thanks for all answers!



</details>


# 答案1
**得分**: 22

将标准输出(stdout)和标准错误(stderr)合并为一个读取器，将一个管道分配给Command.Stdout和Command.Stderr：

    cmdReader, err := cmd.StdoutPipe()
    cmd.Stderr = cmd.Stdout

<details>
<summary>英文:</summary>

To combine stdout and stderr to a single reader, assign a single pipe to Command.Stdout and Command.Stderr:

    cmdReader, err := cmd.StdoutPipe()
    cmd.Stderr = cmd.Stdout

</details>



# 答案2
**得分**: 0

使用函数[`io.MultiReader`][1]将多个读取器合并为一个：

    outReader, err := cmd.StdoutReader()
    if err != nil {
        // 处理错误
    }

    errReader, err := cmd.StderrReader()
    if err != nil {
        // 处理错误
    }

    cmdReader := io.MultiReader(outReader, errReader)


  [1]: https://golang.org/pkg/io/#MultiReader

<details>
<summary>英文:</summary>

Use the function [`io.MultiReader`][1] to combine multiple readers into one:

    outReader, err := cmd.StdoutReader()
    if err != nil {
        // handle err
    }

    errReader, err := cmd.StderrReader()
    if err != nil {
        // handle err
    }

    cmdReader := io.MultiReader(outReader, errReader)


  [1]: https://golang.org/pkg/io/#MultiReader

</details>