查看linux系统版本

参考：

https://blog.csdn.net/majianting/article/details/122694130

https://blog.csdn.net/GSWWJM/article/details/119727346?spm=1001.2101.3001.6650.2&utm_medium=distribute.pc_relevant.none-task-blog-2%7Edefault%7EBlogCommendFromBaidu%7ERate-2-119727346-blog-122694130.pc_relevant_vip_default&depth_1-utm_source=distribute.pc_relevant.none-task-blog-2%7Edefault%7EBlogCommendFromBaidu%7ERate-2-119727346-blog-122694130.pc_relevant_vip_default&utm_relevant_index=3