下载校验与命令行
MD5
5b032ba7c7682627bfafae5fb43243a5
SHA256
e7945b6efa7b03ea78bbf0d2a13ea30b235749860479c37d50aeb4e4e81c2d63
curl -O https://secure-appldnld.apple.com/iOS8.1/031-09535.20141020.XaY73/iPhone4,1_8.1_12B411_Restore.ipsw
# 校验文件完整性
md5sum iPhone4,1_8.1_12B411_Restore.ipsw # 期望 5b032ba7c7682627bfafae5fb43243a5