Description

Pdlzip is a permissively licensed implementation of the lzip data
compressor, intended for those who can't distribute (or even use) GPL
licensed Free Software. (The name of pdlzip comes from 'public domain
lzip'). Pdlzip is written in C and is (hope)fully compatible with lzip 1.4
or newer.

Lzip is a lossless data compressor with a user interface similar to the
one of gzip or bzip2. Lzip can compress about as fast as gzip (lzip -0)
or compress most files more than bzip2 (lzip -9). Decompression speed is
intermediate between gzip and bzip2. Lzip is better than gzip and bzip2
from a data recovery perspective. Lzip has been designed, written and
tested with great care to replace gzip and bzip2 as the standard
general-purpose compressed format for unix-like systems.

The lzip file format is designed for data sharing and long-term archiving,
taking into account both data integrity and decoder availability:

   * The lzip format provides very safe integrity checking and some data
     recovery means. The lziprecover program can repair bit flip errors
     (one of the most common forms of data corruption) in lzip files,
     and provides data recovery capabilities, including error-checked
     merging of damaged copies of a file.

   * The lzip format is as simple as possible (but not simpler). The
     lzip manual provides the source code of a simple decompressor
     along with a detailed explanation of how it works, so that with
     the only help of the lzip manual it would be possible for a
     digital archaeologist to extract the data from a lzip file long
     after quantum computers eventually render LZMA obsolete.

   * Additionally the lzip reference implementation is copylefted, which
     guarantees that it will remain free forever.

A nice feature of the lzip format is that a corrupt byte is easier to
repair the nearer it is from the beginning of the file. Therefore, with
the help of lziprecover, losing an entire archive just because of a
corrupt byte near the beginning is a thing of the past.

Pdlzip is also able to decompress legacy lzma-alone (.lzma) files.
Lzma-alone is a very bad format; it is essentially a raw LZMA stream.
If you keep any lzma-alone files, it is advisable to recompress them to
lzip format. Lziprecover can convert some lzma-alone files to lzip format
without recompressing.

Pdlzip includes public domain (de)compression code from the LZMA SDK
(Software Development Kit) written by Igor Pavlov.

I would not write non-copylefted software unless it is too simple to be
worth copylefting it, but one of the uses of the lzip format is the
interchange of information, and it is therefore desirable that even the
users of the most non-free platforms can share lzip files with everybody
else.


Copyright (C) 2010-2019 Antonio Diaz Diaz.

This file is free documentation: you have unlimited permission to copy,
distribute and modify it.

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