No os.copy()? Why not?

[Nobody]

On Wed, 04 Apr 2012 08:14:18 -0400, Roy Smith wrote:

>> And sparse files are really hard to reproduce, at least on Unix: on
>> Linux even the system's cp doesn't guarantee sparseness of the copy (the
>> manual mentions a "crude heuristic").
> 
> I imagine the heuristic is to look for blocks of all zeros.

Yes. Although it's not really accurate to describe it as a "heuristic".

With --sparse=always, it will try to make the output sparse regardless of
whether the input was sparse, replacing any all-zeros block with a hole.

The default of --sparse=auto will only create a sparse file if the input
itself is sparse, i.e. if the length of the file rounded up to the nearest
block exceeds its disk usage.

Regardless of the --sparse= setting and whether the input was sparse, if
it tries to create a sparse file it will create holes wherever possible
rather than attempting to preserve the exact pattern of holes in a sparse
input file.