You can do exactly that, yes, dd whole disk to external drive, dd it back. Of course this assumes you'll be buying the same laptop, otherwise, you'll have to r

You can do exactly that, yes, dd whole disk to external drive, dd it back. Of course this assumes you'll be buying the same laptop, otherwise, you'll have to reconfigure stuff, from graphics drivers, resolution etc., resize the partitions (assuming the new hdd is larger, and you can't use a smaller one). The problem with dd is, that you can't really run it on a running system, because stuff is constantly being written to the drive (this is same for rsync too, but usualy the damage is smaller), so you have to boot a live linux from usb, dd the whole drive to an external drive, and then after swimming ashore, boot a live linux on the new laptop, and dd the backup to the new drive.