Instead of /tmp/sdadisk.img, you could store it for example at /sdadisk.img if you want. You can store the output file where you want but you have to give a filename ending with. Also, disk image makes the restoration much easier.

Backing up a disk to an image will be faster than copying the exact data. You can create an image of a disk or a file image. The sync option allows to use synchronized I/O. The conv value parameter noerror allows the tool to continue to copy the data even though it encounters any errors.

If you don't specify block size, dd use a default block size of 512 bytes. Make sure you use block sizes in multiples of 1024 bytes which is equal to 1KB. Here, if stands for input file, of stands for output file and bs stands for the block size (number of bytes to be read/write at a time). Otherwise, you get truncated and worthless partitions on the second one. This works only if the second device is as large as or larger than the first. So, this will clone the disk with the same data on the same partition. You need to indicate the block size to be copied at time with bs option. dd doesn’t know anything about the filesystem or partitions it will just copy everything from /dev/sda to /dev/sdb. You can copy all the data (entire disk) from the disk /dev/sda to /dev/sdb. Not a simple copy as cp command but a block size copy. It is possible to save all the data from an entire disk/partition to another disk/partition. Backing up and restoring an entire disk or a partition We will learn various options while going through dd command examples. However, you can use it to clone a hard disk. The arguments to those options can be either files or block devices. I would, however, not recommend using dd to copy files because cp does that in a much simpler way. The basic use of the dd command is rather easy because it takes just two arguments: if= to specify the input file and of= to specify the output file. So, some people consider this tool as data destroyer. You should be very careful while using this command as improper usage may cause huge data loss. Only the superuser can execute this command.

Converting lowercase to uppercase and vice versa.Converting data formats like ASCII to EBCDIC.Copy regions of raw device files like backing up MBR (master boot record).Creating virtual filesystem and backup images of CD or DVDs called ISO files.Backing up and restoring an entire hard drive or a partition.This tool is mainly used for copying and converting data, hence it stands for data duplicator. The Linux dd command is one of the most powerful utility which can be used in a variety of ways.

Identify zero byte file unix