runssh-working.go

package main

import (
	"fmt"
	"os"
	"os/exec"
	"os/signal"
	"syscall"
	"time"
	"unsafe"
)

func Tcsetpgrp(fd int, pid int) error {
	_, _, errno := syscall.RawSyscall(syscall.SYS_IOCTL, uintptr(fd),
		uintptr(syscall.TIOCSPGRP), uintptr(unsafe.Pointer(&pid)))
	if errno == 0 {
		return nil
	}

	return errno
}

func main() {
	var err error

	tty, err := os.OpenFile("/dev/tty", os.O_RDWR, 0600)
	if err != nil {
		panic(err)
	}

	fmt.Printf("tty fd is %d\n", int(tty.Fd()))

	pid := syscall.Getpid()
	group := syscall.Getpgrp()

	fmt.Printf("pid is %d, group is %d\n", pid, group)

	cmd := exec.Command("ssh", "localhost", "echo 'remote: start'; sleep 20; echo 'remote: done'")
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr

	cmd.SysProcAttr = &syscall.SysProcAttr{
		Setpgid: true,
	}

	ch := make(chan os.Signal)
	signal.Notify(ch, syscall.SIGINT)
	signal.Ignore(syscall.SIGTTIN)
	signal.Ignore(syscall.SIGTTOU)

	go func() {
		for sig := range ch {
			fmt.Printf("main: signal received: %v\n", sig)
		}
	}()

	err = cmd.Start()
	if err != nil {
		fmt.Printf("main: start returned err: %v\n", err)
	}

	fmt.Printf("switching foreground process group to %d\n", cmd.Process.Pid)
	err = Tcsetpgrp(int(tty.Fd()), cmd.Process.Pid)
	if err != nil {
		panic(err)
	}

	time.Sleep(5 * time.Second)
	err = Tcsetpgrp(int(tty.Fd()), group)
	if err != nil {
		panic(err)
	}
	fmt.Printf("switched foreground process group back to %d\n", group)

	err = cmd.Wait()
	if err != nil {
		fmt.Printf("main: wait returned err: %v\n", err)
	}
}