This nearly tells you all you need to know. The other bit of info you'll want to note is that head -c +N produces as many bytes as you ask. So if you try to get

This nearly tells you all you need to know. The other bit of info you'll want to note is that head -c +N produces as many bytes as you ask. So if you try to get the prefix using "head -c +N" and the suffix using "tail -c +N" then you'll have 1 byte of overlap. (dd's corresponding options do not suffer from this problem.)