centos7 /dev/tty /dev/console /dev/ttyx

1. /dev/tty 表明當前tty，包括僞終端pts
2. /dev/tty0和 /dev/console表明當前tty，不包括僞終端
3. 用echo測試驗證 如echo "test" > /dev/console

參考：
http://www.javashuo.com/article/p-gpmliqit-bh.html
https://unix.stackexchange.com/questions/60641/linux-difference-between-dev-console-dev-tty-and-dev-tty0