cat /etc/issue
6是squeeze
7是wheezy
8是jessie
http://downloads.raspberrypi.org/raspbian/images/
https://aoenian.github.io/2018/05/20/rasp-versions/
getconf LONG_BIT # 查看系统位数
uname -a # kernel 版本
/opt/vc/bin/vcgencmd version # firmware版本
strings /boot/start.elf | grep VC_BUILD_ID # firmware版本
cat /proc/version # kernel
cat /etc/os-release # OS版本资讯
cat /etc/issue # Linux distro 版本
cat /etc/debian_version # Debian版本编号
