Remove x number of lines from beginning of file

[Dave Smith]

Steve wrote:
> This code is much improved...
>   

The point wasn't to do what sed does, only a little faster, because the 
approach is all wrong. The point is to find a solution that can remove 
the first few lines of a huge file without copying the whole rest of the 
file. In CS speak, we're talking constant vs. linear. In my view, the 
best solution would involve a file system hack as has already been 
proposed. The fuse and loopback options seem most promising.

In other words, you could optimize this C++ code all day long, and it 
won't make any significant difference because you're still bound by the 
linear operation of copying most of the file.

--Dave