下载校验与命令行
SHA256
534f27d96c02543b929be53075214d2289d0e96ae2b7f649069ff5d65367945e
curl -O https://old-releases.ubuntu.com/releases/dapper/ubuntu-6.06.2-server-amd64.iso
# 校验文件完整性
md5sum ubuntu-6.06.2-server-amd64.iso # 期望