dd命令介绍
参考文档：
https://blog.csdn.net/jks212454/article/details/125074067?ops_request_misc=&request_id=&biz_id=&utm_medium=distribute.pc_search_result.none-task-blog-2~blog~koosearch~default-1-125074067-null-null.268^v1^koosearch&utm_term=dd&spm=1018.2226.3001.4450