How to create holes in files ?

[Bob Eager]

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On Thu, 28 Sep 2017 17:26:09 +0200
Fabian Keil <freebsd-listen at fabiankeil.de> wrote:

> Ben RUBSON <ben.rubson at gmail.com> wrote:
> 
> > I'm trying to make holes in files in C.
> > Goal is to deallocate huge files on ZFS while (randomly) reading
> > them.  
> 
> My interpretation of the above is that you want to create holes
> without changing the file size and without affecting data that
> is located before or after the holes that you want to create.
> 
> Otherwise you could simply "deallocate" the content with
> truncate(1).

If he doesn't mind copying the files, dd(1) will do the job. However, I
expect that doesn't meet his criteria.
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