get current baud rate of tty/serial device in linux via ioctl syscall

getBaud.go

package main

import (
	"os"
	"strconv"

	"golang.org/x/sys/unix"
)

func getBaudRate(name string) (int, error) {
	fd, err := unix.Open(name, unix.O_RDONLY|unix.O_NONBLOCK|unix.O_LARGEFILE, 0)
	if err != nil {
		return 0, err
	}

	term, err := unix.IoctlGetTermios(fd, unix.TCGETS2)
	unix.Close(fd)

	if err != nil {
		return 0, err
	}
	
	return int(term.Ispeed), nil
}

func main() {
	target := "/dev/tty0"
	if len(os.Args) > 1 {
		target = os.Args[1]
	}

	res, err := getBaudRate(target)
	if err != nil {
		println(err.Error())
		return
	}

	println(target + " baud rate: " + strconv.Itoa(res))
}