How do I truncate a file, delete bytes, or set the end of file from a stream?

[XP1]

On Sun, 12 Jun 2011 02:47:01 -0400, XP1 <nospam at nospam.com> wrote:

>
> How do I truncate a file, delete bytes, or set the end of file from a  
> stream?
>
> For example, what would be the easiest way to delete the last 4 bytes  
> from a file?

Anyone?