执行docker build 时，第三步提示no such file or directory

Question

从网站上下载的脚本，脚本如下FROM scratchMAINTAINER The CentOS Project <[e-mail]>ADD c68-docker.tar.xz /LABEL name="CentOS Base Image" \vendor="CentOS" \license="GPLv2" \build-date="2016-06-02"# Default commandCMD ["/bin/bash"]https://github.com/CentOS/sig-cloud-instance-images/blob/f32666d2af356ed6835942ed753a4970e18bca94/docker/Dockerfile 复制到一个Dockerfile文件中然后执行 docker build -t sssss/ecs6.8执行到第三步时提示lastat c68-docker.tar.xz:no such file or directorydocker 版本信息如下：操作系统版本：centos 7