前往：无法将git的输出传送到自定义管道

Question

I'm trying to forward the Stdout of "git clone somerepo ./" to log. Unfortunately, only the first line gets piped and everything else discarded.

package main

import (
    "os/exec"
    "log"
)


type pipe struct {}

func (p *pipe) Write(d []byte) (n int, err error) {
    log.Printf("Git subcommand: %s", d)
    return len(d), nil
}

func main() {
    e := exec.Command("git", "clone", "https://github.com/some/repo", "./DATA")
    p := &pipe{}
    e.Stdout = p
    e.Stderr = p
    _ = e.Run()
}

This code results in: 2015/04/06 16:47:19 Git subcommand: Cloning into './DATA'...

Whilst a slight modification:

    e.Stdout = os.Stdout
    e.Stderr = os.Stderr

Prints out the correct result (but in the output of the cmd line, not a custom pipe)

Cloning into 'D:\Local\Temp\915593bb-0aae-4678-adf0-56930d519ee1'...
remote: Counting objects: 118, done.
remote: Compressing objects: 100% (16/16), done.
rRemote: Total 118 (delta 7), reused 0 (delta 0), peceiving objects:  38% (45/
Receiving objects:  40% (48/118)
Receiving objects: 100% (118/118), 22.35 KiB | 0 bytes/s, done.
Resolving deltas: 100% (53/53), done.
Checking connectivity... done.
Cloning repository was successful

In both cases, the repository got cloned successfully, just the output isn't being catched right.

CombinedOutput() as well as Output() have the same broken behaviour:

func main() {
    o, err := exec.Command("git", "clone", "https://github.com/some/repo.git", "./DATA").CombinedOutput()
    if err != nil {
        log.Fatal(err)
    }
    log.Printf("%s", o)
}

What am I doing wrong?

---

Using scanners doesn't help either:

func main() {
    e := exec.Command("git", "clone", "https://github.com/some/repo", "./DATA")
    op, _ := e.StdoutPipe()
    ep, _ := e.StderrPipe()
    go func() {
        scanner := bufio.NewScanner(op)
        for scanner.Scan() {
            log.Printf("Scanner got: ", scanner.Text())
        }
    }()
    go func() {
        scanner := bufio.NewScanner(ep)
        for scanner.Scan() {
            log.Printf("Scanner got: %s", scanner.Text())
        }
    }()
    _ = e.Run()
}

Results in:

2015/04/06 16:54:21 Scanner got: Cloning into './DATA'...