I am almost a beginner. And a total idiot.

so i have

done a dd if=/somefile.img of=/dev/sdc1

sdc1 was a USB disk drive with many many files on it i did not want to lose.

What it did was remove the dev/scd1 USB drive and my mounting of /media/movie and then change it to /media/somefile as the new mount point. The file system says UDF.

On reboot this comes up as a totally new mount and I can only see the results of the above .img extraction. (at least that worked)

the somefile.img was 4.4gb and was an image of a DVD.

I have since found out that DD is a unix command. So what did this do to this drive.

For example did it erase the MTF?
It took about 15 min to do so I am assuming it did not write to the whole 1TB that this disk is?
Did it write to the beginning of the disk with only 4.4gb of information?
Thus is it possible that although the other files cannot be seen at the moment some of the file recovery programs may be able to see them? (this last question is not so important as i am back with wondows and trying to do this I am just trying to understand what dd does)