139 lines
4.7 KiB
Plaintext
139 lines
4.7 KiB
Plaintext
$NetBSD: README,v 1.4 1999/07/03 12:30:16 simonb Exp $
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This is the README for bzip2, a block-sorting file compressor, version
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0.9.0. This version is fully compatible with the previous public
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release, bzip2-0.1pl2.
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bzip2-0.9.0 is distributed under a BSD-style license. For details,
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see the file LICENSE.
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Complete documentation is available in Postscript form (manual.ps)
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or html (manual_toc.html). A plain-text version of the manual page is
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available as bzip2.txt.
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HOW TO BUILD -- UNIX
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Type `make'.
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This creates binaries "bzip2" and "bzip2recover".
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It also runs four compress-decompress tests to make sure things are
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working properly. If all goes well, you should be up & running.
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Please be sure to read the output from `make' just to be sure that the
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tests went ok.
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To install bzip2 properly:
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* Copy the binaries "bzip2" and "bzip2recover" to a publically visible
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place, possibly /usr/bin or /usr/local/bin.
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* In that directory, make "bunzip2" and "bzcat" be symbolic links
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to "bzip2".
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* Copy the manual page, bzip2.1, to the relevant place.
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Probably the right place is /usr/man/man1/.
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If you want to program with the library, you'll need to copy libbz2.a
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and bzlib.h to /usr/lib and /usr/include respectively.
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HOW TO BUILD -- Windows 95, NT, DOS, Mac, etc.
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It's difficult for me to support compilation on all these platforms.
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My approach is to collect binaries for these platforms, and put them
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on my web page (http://www.muraroa.demon.co.uk). Look there.
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VALIDATION
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Correct operation, in the sense that a compressed file can always be
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decompressed to reproduce the original, is obviously of paramount
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importance. To validate bzip2, I used a modified version of Mark
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Nelson's churn program. Churn is an automated test driver which
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recursively traverses a directory structure, using bzip2 to compress
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and then decompress each file it encounters, and checking that the
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decompressed data is the same as the original. There are more details
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in Section 4 of the user guide.
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Please read and be aware of the following:
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WARNING:
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This program (attempts to) compress data by performing several
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non-trivial transformations on it. Unless you are 100% familiar
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with *all* the algorithms contained herein, and with the
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consequences of modifying them, you should NOT meddle with the
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compression or decompression machinery. Incorrect changes can and
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very likely *will* lead to disastrous loss of data.
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DISCLAIMER:
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I TAKE NO RESPONSIBILITY FOR ANY LOSS OF DATA ARISING FROM THE
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USE OF THIS PROGRAM, HOWSOEVER CAUSED.
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Every compression of a file implies an assumption that the
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compressed file can be decompressed to reproduce the original.
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Great efforts in design, coding and testing have been made to
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ensure that this program works correctly. However, the complexity
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of the algorithms, and, in particular, the presence of various
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special cases in the code which occur with very low but non-zero
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probability make it impossible to rule out the possibility of bugs
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remaining in the program. DO NOT COMPRESS ANY DATA WITH THIS
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PROGRAM UNLESS YOU ARE PREPARED TO ACCEPT THE POSSIBILITY, HOWEVER
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SMALL, THAT THE DATA WILL NOT BE RECOVERABLE.
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That is not to say this program is inherently unreliable. Indeed,
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I very much hope the opposite is true. bzip2 has been carefully
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constructed and extensively tested.
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PATENTS:
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To the best of my knowledge, bzip2 does not use any patented
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algorithms. However, I do not have the resources available to
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carry out a full patent search. Therefore I cannot give any
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guarantee of the above statement.
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End of legalities.
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WHAT'S NEW IN 0.9.0 (as compared to 0.1pl2) ?
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* Approx 10% faster compression, 30% faster decompression
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* -t (test mode) is a lot quicker
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* Can decompress concatenated compressed files
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* Programming interface, so programs can directly read/write .bz2 files
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* Less restrictive (BSD-style) licensing
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* Flag handling more compatible with GNU gzip
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* Much more documentation, i.e., a proper user manual
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* Hopefully, improved portability (at least of the library)
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I hope you find bzip2 useful. Feel free to contact me at
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jseward@acm.org
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if you have any suggestions or queries. Many people mailed me with
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comments, suggestions and patches after the releases of bzip-0.15,
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bzip-0.21 and bzip2-0.1pl2, and the changes in bzip2 are largely a
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result of this feedback. I thank you for your comments.
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At least for the time being, bzip2's "home" is
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http://www.muraroa.demon.co.uk.
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Julian Seward
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jseward@acm.org
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Manchester, UK
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18 July 1996 (version 0.15)
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25 August 1996 (version 0.21)
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Guildford, Surrey, UK
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7 August 1997 (bzip2, version 0.1)
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29 August 1997 (bzip2, version 0.1pl2)
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23 August 1998 (bzip2, version 0.9.0)
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