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Re: [GUG] Gimp version

_____/ On Thu 10 Nov 2005 22:51:03 GMT, [The Digital Pioneer] wrote : \_____

On 11/10/05, Marc 'BlackJack' Rintsch <marc@xxxxxxxxxx> wrote:

On Wednesday 09 November 2005 15:26, The Digital Pioneer wrote:

> I don't know to what depth you wanted information on tarballs, but
> I'll go a little into the science of them that I know personally.
> A tarball is a file of files, basically. Somewhat like a zip file,
> but bigger. Tarballs are simple concatencation. Then just put a bunch
> of files together into 'a big ball of files' or a tarball. Tarballs
> have the extension .tar.
> .gz files are a little different... .gz is actual compression. It
> makes the output file smaller. I don't know why they don't just make
> a .zip file and be done with it... Maybe Linux doesn't support that.

Of course one can create ZIP files on any system with a C compiler to
compile the (un)zip software. There's even a (un)zipper for the
Commodore64 (8-Bit processor @~1Mhz, 64kBRAM).

An advantage of `tar` files is that combining files to one big tarball
and then compressing the whole, instead of each individual file like
ZIP, yields a smaller archive because the compression algorithm can
exploit redundancies across files.

I don't know if ZIPs can preserve all Unix file types and file
attributes. So that may be another reason to use `tar` on Unix
systems. I guess the same is true for StuffIt (`*.sit`) archives for
Mac systems.

And separating the archive format from the compression has the advantage
that the compression can be changed easily, e.g. from `gzip` to the
slower but better `bzip2`, and compression can be applied to
non-archive files. This can be used in GIMP by loading/saving
compressed images as `*.xcf.gz`.

Marc 'BlackJack' Rintsch

Bottom line, what do you think is the most effective method of compression?

My experience, which is based on several packages that I compress as .tar.gz and .zip (for Windows users), is that .tar.gz is a stronger com- pression. This may vary depending on the versions used and the pattern of files, but the compression for ZIP archive is quite high, which makes it unbiased:

zip -r -9 ./file.zip dir/ ;


tar czvf ./file.tar.gz dir/ ;

The latter produces a smaller file, which is rapidly openable using Ark or
the  like (GNOME has good extraction tools as well). I have no idea how  a
discussion  on  GIMP downloads reached an in-depth argument over  compres-
sion, but it has been interesting nonetheless.


Roy S. Schestowitz
http://Schestowitz.com  |    SuSE Linux     |     PGP-Key: 0x74572E8E
 1:45pm  up 8 days  9:43,  4 users,  load average: 0.25, 0.29, 0.22

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