docker 的cp命令可以從容器往外復制，也可以從本機復制的容器。
docker cp 文件路徑 容器id:/容器目錄
docker help cp Usage: docker cp [OPTIONS] CONTAINER:PATH LOCALPATH|- docker cp [OPTIONS] LOCALPATH|- CONTAINER:PATH Copy files/folders between a container and your host. Use '-' as the source to read a tar archive from stdin and extract it to a directory destination in a container. Use '-' as the destination to stream a tar archive of a container source to stdout.