Use Linux dd to copy and read file at specified location

Question

I want to use the dd command to write one file at any location of the hard drive and then to read the same file from this location. I need to be independent on any file system or partitioning. It seems not easy to do this. The prerequisites are:

1. In order to do this I need to be able to navigate on the hard drive. The compass would be the sectors, let's say 1 sector = 512 B.
2. The file size is, let's say 150 B. Simple text file.
3. I want to write this file starting from 2099200 sector.

I tried this:

sudo dd if=my.txt of=/dev/sdb obs=512 seek=2099199
sudo dd if=/dev/sdb of=my.txt obs=150 count=1 ibs=512 skip=2099199

but it is not working because I can not make it read only 150 B, because of the ibs count which is 512 B. I need this count in order to easily navigate on the hard drive so it must be 512 B.

Is there an easy way to handle this case with dd? Or maybe there is another command or way to do this? I need to be independent on any kind of file systems and partitioning.

Solution

You may use this one to seek bytes (2099199*512) not bs count.

dd if=your.txt of=/dev/sdb count=1 bs=150 oflag=seek_bytes seek=1074789888 

and

dd if=/dev/sdb of=your.txt count=1 bs=150 iflag=skip_bytes skip=1074789888 

See man dd.

---

Then what about:

dd if=your.txt of=/dev/sdb bs=1 count=150 seek=1074789888 

and

dd if=/dev/sdb of=your.txt bs=1 count=150 skip=1074789888 

Comments

[ncheltsov]

unfortunately my version of dd seems not having this flags.