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Re: possible problem with dpkg-genchanges

Previously Thomas Bushnell, BSG wrote:
> Module filesystem holes, a decent solution is to declare the actual
> sizes of each program, and have dpkg/apt print out a correct
> computation based on the filesystem behavior of the local system.

That's just as bad, since it means the files will actually use up
more space on your filesystem. How much space is used depends on:
1. the actual size of a file (duh)
2. the blocksize of the filesystem
3. filesystem characteristics (think tailpacking)

Also you need the multiple the maximum error as a result of the above 3 
with the number of files in the package to get total error in
installed-size for a package.

So if you want to know exactly how much space a package will use
you need to know the exact fs characteristics and its blocksize
and walk over all files in a package. And even then you might be off
since tail packing might produce slightly different optimizations
depending on what other processes on your system do when you are

To summarize: install-size is basically a good heuristic (best guess)
for how much space a package will take, and trying to figure out how
much space will exactly be used will take a lot more effort than it
is worth.


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