Chris Gther schrieb:
> That's exactly the solution I already have. What I dont like about this 
> solution is that you have to open and close file descriptors 3 times 
> just for patching one little file (For sure a working solution but quite 
> some overhead).

In order to patch an existing file, all you have to do is

>>   File.open(FNAME,"rb+") {|fd|
>>       fd.pos=OFFSET
>>       fd.write(VALUE)
>>       p "written modified piece of data = '#{VALUE}'"
>>   }

The other File.open calls are for creating the test file and for testing 
the contents of the patched file. I copied them from your initial 
script. Of course you could do all three steps (create, patch, test) in 
a single File.open block.

Regards,
Pit