Run interactive shell script in golang program

Question

I want to run an interactive shell script in golang program, such as wrap a "ping 8.8.8.8", "python", "bc", "mysql -H -P -u -p". The golang program should exit when itself finish calling an interactive command,or shell, and leaving spawned interactive with user.

I have tried the "exec.Command("python").Run()", but the golang program just finish and leave nothing to me.

func (h ConnectHandler)ConnectMySQL()  {
    logrus.Debug("ConnectMySQL, script:",common.CONF.FilePath.MySQLConnectScriptPath)
    err :=exec.Command("bash",common.CONF.FilePath.MySQLConnectScriptPath).Run()
    if err != nil{
        logrus.Errorf("ConnectMySQL failed, exit 1,%s",err)
        os.Exit(1)
    }
}

Eerik Sven Puudist · Accepted Answer · 2020-11-12 00:13:27Z

26

Connect the Command's stdin, stdout, and stderr to those of the parent process. Also, supply -c in exec.Command to bash, else bash will try to run your program as if it's a shell script.

For example launching the interactive Python console:

func main() {
    fmt.Println("Before Python shell:")
    cmd := exec.Command("bash", "-c", "/usr/bin/python3")
    cmd.Stdin = os.Stdin
    cmd.Stdout = os.Stdout
    cmd.Stderr = os.Stderr
    _ = cmd.Run() // add error checking
    fmt.Println("After Python shell")
}

edited Nov 12, 2020 at 0:13

Eerik Sven Puudist

2,3762 gold badges29 silver badges46 bronze badges

answered Feb 29, 2020 at 14:20

Shang Jian Ding

2,15617 silver badges25 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Eerik Sven Puudist Over a year ago

This method works perfectly. I do not understand, why it has not received any upvotes.

David Maze · Accepted Answer · 2020-03-01 14:03:50Z

7

It sounds like you want to replace the current process with the command you're trying to launch. After you launch the other command, your Go program is gone, and the caller interacts with the launched program as if it were the thing that was initially started.

You need the low-level syscall.Exec function for this. You shouldn't normally expect it to return. Note that you need to provide a number of details like the actual binary to run and the environment that the higher-level wrappers don't need. (A very quick Google search finds this detailed writeup.)

import "os"
import "syscall"
err := syscall.Exec("/bin/ls", []string{"ls", "-l", "/"}, os.Environ())
// We don't expect this to ever return; if it does something is really wrong
os.panic(err)

In terms of the underlying Unix system calls, the higher-level interfaces like os.StartProcess and the exec.Cmd all fork(2) a child process first before execve(2) in that child. When your Go process exits, that child process becomes orphaned, and the system init process becomes its new parent. The shell just sees that the Go process has exited and will produce a new shell prompt.

answered Mar 1, 2020 at 14:03

David Maze

165k47 gold badges262 silver badges302 bronze badges

2 Comments

Panic Over a year ago

what's the difference between the answer below using Connect the Command's stdin, stdout, and stderr to those of the parent process?

David Maze Over a year ago

In my answer there is no "parent process"; the Go program replaces itself with the exec'd program, and the parent and process ID are the same as it was for the Go program. In @ShengjianDing's answer the Go program remains and becomes the parent of the subprocess; it's responsible for checking the error status and other tasks.

Collectives™ on Stack Overflow

Run interactive shell script in golang program

2 Answers 2

1 Comment

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related