运行os.execute以获取输出

Question

Im using the following code which run command against binary and need to provide output

if I run the command ftr get apps in the in my mac I got

[app1 apps2]

Now I copy the binary to the test data folder and run the code below and I want to get the apps, currenlty there is no error but Im not getting also the data, what could be missing here?

    Cmd := exec.Command("ftr", "get", "apps")
    Cmd.Dir = "./testdata/"
    err := Cmd.Start()
    fmt.Println(err)
    bytes, e := Cmd.Output()
    fmt.Println(bytes, e)

Answer 1

You won't directly have an output, since the commands takes some time before it writes in stdout/stderr, so you need to basically wait for something to come out.

The way you can do it is by using bufio.NewScanner, like this:

package main

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

func main() {
    args := "get apps"
    cmd := exec.Command("ftr", strings.Split(args, " ")...)
    cmd.Dir = "./testdata/"

    stdout, _ := cmd.StdoutPipe()
    cmd.Start()

    scanner := bufio.NewScanner(stdout)
    scanner.Split(bufio.ScanWords)

    for scanner.Scan() {
        m := scanner.Text()
        fmt.Println(m)
    }

    cmd.Wait()
}

If your command writes on stderr instead of stdout, you might need to use cmd.StderrPipe instead of cmd.Stdoutpipe in order to get the output.