os/exec: StdinPipe on Windows is not successful

[liwux]

Please answer these questions before submitting your issue. Thanks!

What version of Go are you using (go version)?

Go 1.8

My code:

package main
import (

	"os"
	"os/exec"
	"io"
)
func main() {
	command :="openconnect"
	param := []string{"https://192.168.0.100:1443","-u","test","--passwd-on-stdin"}
	cmd :=exec.Command(command,param...)
	cmd.Stdout = os.Stdout
	input, _ := cmd.StdinPipe()
	cmd.Start()
	io.WriteString(input,"123\n")
	cmd.Wait()
}

can not automatically standard input when the command starts.

I changed a kind of writing

the code

package main

import (
	"fmt"
	"io"
	"log"
	"os/exec"
	"os"
)

func main() {
	command :="openconnect"
	param := []string{"https://192.168.0.100:1443","-u","test","--passwd-on-stdin"}
	cmd :=exec.Command(command,param...)
	stdin, err := cmd.StdinPipe()
	if err != nil {
		log.Fatal(err)
	}
	go func() {
		defer stdin.Close()
		io.WriteString(stdin, "123\n")
	}()
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr
	if err = cmd.Start(); err != nil { //Use start, not run
		fmt.Println("An error occured: ", err) //replace with logger, or anything you want
	}
	cmd.Wait()

}

The two are not successful .
when I input "123" by Keyboard ,is ok.
who can help me,thanks.

[mvdan]

Did you find a specific bug in the standard library? If so, please provide a shorter piece of code to reproduce it.

Otherwise, please take it to https://github.com/golang/go/wiki/Questions as that's where you should go for chunks of code that don't work as you expected. It's likely an issue with your code.

[ianlancetaylor]

You say "are not successful" but you don't say what happens. What precisely happens? Do you get an error? Does the program misbehave in some way?

I don't understand your program: you call StdinPipe but you don't write anything to the pipe. What are you really trying to do?

[liwux]

@ianlancetaylor I don't get any error , just don't write anything to the pipe
What's the problem with this :

stdin, err := cmd.StdinPipe()
io.WriteString(stdin, "123\n")

[ianlancetaylor]

I apologize, I did miss the fact that you do write to the pipe.

I tried running this variant of your program on GNU/Linux, and it printed 123. I do not know why your program is not working. I don't know what the openconnect program is.

package main

import (
        "fmt"
        "io"
        "log"
        "os/exec"
        "os"
)

func main() {
        command :="cat"
        param := []string{}
        cmd :=exec.Command(command,param...)
        stdin, err := cmd.StdinPipe()
        if err != nil {
                log.Fatal(err)
        }
        go func() {
                defer stdin.Close()
                io.WriteString(stdin, "123\n")
        }()
        cmd.Stdout = os.Stdout
        cmd.Stderr = os.Stderr
        if err = cmd.Start(); err != nil { //Use start, not run
                fmt.Println("An error occured: ", err) //replace with logger, or anything you want
        }
        cmd.Wait()

}

[ianlancetaylor]

Two things you should certainly do are check the error return of io.WriteString and cmd.Wait.

[liwux]

@ianlancetaylor Run on GNU/Linux and OSX and it printed 123 ,but run on windows it printed nothing

[liwux]

@ianlancetaylor thanks...
it may be the openconnect program's problem

[jD91mZM2]

I'm an idiot, so don't trust anything I say.
But maybe... just maybe it's because you need \r\n on Windows?

[bradfitz]

I'm going to close this for now until there's evidence pointing at it being Go's problem.

Feel free to reopen if you have more info.