- 销毁磁盘数据
dd if=/dev/urandom of=/dev/sdb - 备份和恢复磁盘数据
dd if=/dev/sda | gzip > image.gz
gzip -d --stdout image.gz | dd of=/dev/sdc - ibs 输入块大小
obs 输出块大小
skip : skip N ibs-sized blocks at the start of input
seek : skip N obs-sized blocks at the start of output