I'm certainly not telling anything new here, but it is probably worth
mentioning that a part of Hubert Feyrer's g4u Documentation discusses
this subject:

http://www.feyrer.de/g4u/#shrinkimg

Tom



Steven M. Bellovin schrieb:
> In message <200408021146.14474.junyoung@mogua.com>, Bang Jun-Young writes:
> 
>>Hi,
>>
>>Is there a disk wipe out utility for NetBSD, a program that fills
>>unused blocks of the file system with 0 without destroying data?
>>It's mostly used for security but I need it for backup purpose
>>so the entire image of the NetBSD partition is compressed in less
>>size.
>>
> 
> I haven't seen one, but it would be very easy to write a simple one -- 
> create a file, and go into a loop writing a zero byte every 512 bytes.  
> In fact, if you want to go through the file system instead of writing 
> to the raw disk it's hard to see how to make it any better.