Wipe first and last megabyte of file

[lladlu]

I need some kind of tool to overwrite the first and last megabyte of a file several times.
I was thinking about using dd in a script, but I'm not so experienced with it, and the man-page does not show something useful (for this job).

I've also looked into shred, since I read this on the man-page:

-s, --size=N
shred this many bytes (suffixes like K, M, G accepted)

But I'm not sure if that would delete from the beginning or the end, or event what this command exactly does.

Edit: Sorry if this is the wrong subforum, I couldn't figure out whether to use this or Misc.

[jayd512]

dd would probably be your best bet here.
But I would be careful about using it in a script unless you're very sure about how you're writing it!
You can find some decent dd tutorials using Google.