The two programs, however, only do the same thing if you consider that they're both compressors. bzip2 eats much more resources than gzip, both space and time. And the algorithm is rather overkill for small files anyways.
Granted, the space savings is not that much. I took /usr/share/man/man1 from a 4.6.2-RELEASE box and made three copies of it under /tmp/man, uncompressed all the files, and then re-compressed them using `compress`, `gzip -9`, and `bzip2`. Here's the results:
% du * | sort -nr
4646 compress
3624 gzip
3422 bzip2So, bzip2 is not that much of an improvement over gzip (~6%), but it is a fair improvement over compress (~35.7%). This is just one section of the man pages, and does not include the cat pages, but I figure it's probably fairly representative.
I haven't looked at the stuff under /usr/share/info or /usr/share/doc. I'm not sure which of those files would be compressed and which ones wouldn't. These three directories comprise ~82MB of disk space, of which about 15MB is in /usr/share/man and about 64.6MB in /usr/share/doc. At the moment, it doesn't appear that the files in /usr/share/doc are compressed at all, so there might be significant storage savings there.
I built a tarball from the /usr/share/doc hierarchy, and tried the three different compression programs on it. I know that compression on a tarball is going to be different from compression on individual files, but this should at least give us some idea.
Anyway, here's the results:
% ls -1s doc* | sort -nr
64368 doc.tar
22896 doc-compress.tar.Z
16080 doc-gzip.tar.gz
12032 doc-bzip2.tar.bz2So, bzip2 result in a file about 18.6% of the size of the original, gzip does about 24.9%, and compress is only 35.5%. Relatively speaking, bzip2 results in a file that is about 74.8% the size of the version produced by `gzip -9`.
Seeing as /usr/share/doc and /usr/share/info is not currently compressed (in 4.6.2-RELEASE), any compression algorithm would be a significant improvement.
-- Brad Knowles, <[EMAIL PROTECTED]>
"They that can give up essential liberty to obtain a little temporary
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