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authorDaniel Baumann <daniel.baumann@progress-linux.org>2021-01-27 15:59:05 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2021-01-27 15:59:39 +0000
commitcfb04b6a293e8e21107bcc938021275d0647637c (patch)
tree1854024289aab6a68bdb19dc9f385cf405e5cbdb /README
parentReleasing debian version 1.8-8. (diff)
downloadplzip-cfb04b6a293e8e21107bcc938021275d0647637c.tar.xz
plzip-cfb04b6a293e8e21107bcc938021275d0647637c.zip
Merging upstream version 1.9.
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'README')
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1 files changed, 56 insertions, 50 deletions
diff --git a/README b/README
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--- a/README
+++ b/README
@@ -1,30 +1,36 @@
Description
Plzip is a massively parallel (multi-threaded) implementation of lzip, fully
-compatible with lzip 1.4 or newer. Plzip uses the lzlib compression library.
-
-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.
-
-Plzip can compress/decompress large files on multiprocessor machines
-much faster than lzip, at the cost of a slightly reduced compression
-ratio (0.4 to 2 percent larger compressed files). Note that the number
-of usable threads is limited by file size; on files larger than a few GB
-plzip can use hundreds of processors, but on files of only a few MB
-plzip is no faster than lzip.
-
-When compressing, plzip divides the input file into chunks and
-compresses as many chunks simultaneously as worker threads are chosen,
-creating a multimember compressed file.
+compatible with lzip 1.4 or newer. Plzip uses the compression library lzlib.
+
+Lzip is a lossless data compressor with a user interface similar to the one
+of gzip or bzip2. Lzip uses a simplified form of the 'Lempel-Ziv-Markov
+chain-Algorithm' (LZMA) stream format, chosen to maximize safety and
+interoperability. 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.
+
+Plzip can compress/decompress large files on multiprocessor machines much
+faster than lzip, at the cost of a slightly reduced compression ratio (0.4
+to 2 percent larger compressed files). Note that the number of usable
+threads is limited by file size; on files larger than a few GB plzip can use
+hundreds of processors, but on files of only a few MB plzip is no faster
+than lzip.
+
+For creation and manipulation of compressed tar archives tarlz can be more
+efficient than using tar and plzip because tarlz is able to keep the
+alignment between tar members and lzip members.
+
+When compressing, plzip divides the input file into chunks and compresses as
+many chunks simultaneously as worker threads are chosen, creating a
+multimember compressed file.
When decompressing, plzip decompresses as many members simultaneously as
worker threads are chosen. Files that were compressed with lzip will not
-be decompressed faster than using lzip (unless the '-b' option was used)
+be decompressed faster than using lzip (unless the option '-b' was used)
because lzip usually produces single-member files, which can't be
decompressed in parallel.
@@ -32,34 +38,34 @@ 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.
+ recovery means. The program lziprecover 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.
+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.
Plzip uses the same well-defined exit status values used by lzip, which
makes it safer than compressors returning ambiguous warning values (like
gzip) when it is used as a back end for other programs like tar or zutils.
-Plzip will automatically use for each file the largest dictionary size
-that does not exceed neither the file size nor the limit given. Keep in
-mind that the decompression memory requirement is affected at
-compression time by the choice of dictionary size limit.
+Plzip will automatically use for each file the largest dictionary size that
+does not exceed neither the file size nor the limit given. Keep in mind that
+the decompression memory requirement is affected at compression time by the
+choice of dictionary size limit.
When compressing, plzip replaces every file given in the command line
with a compressed version of itself, with the name "original_name.lz".
@@ -76,28 +82,28 @@ possible, ownership of the file just as 'cp -p' does. (If the user ID or
the group ID can't be duplicated, the file permission bits S_ISUID and
S_ISGID are cleared).
-Plzip is able to read from some types of non regular files if the
-'--stdout' option is specified.
+Plzip is able to read from some types of non-regular files if either the
+option '-c' or the option '-o' is specified.
If no file names are specified, plzip compresses (or decompresses) from
-standard input to standard output. In this case, plzip will decline to
-write compressed output to a terminal, as this would be entirely
-incomprehensible and therefore pointless.
+standard input to standard output. Plzip will refuse to read compressed data
+from a terminal or write compressed data to a terminal, as this would be
+entirely incomprehensible and might leave the terminal in an abnormal state.
Plzip will correctly decompress a file which is the concatenation of two or
more compressed files. The result is the concatenation of the corresponding
decompressed files. Integrity testing of concatenated compressed files is
also supported.
-LANGUAGE NOTE: Uncompressed = not compressed = plain data; it may never
-have been compressed. Decompressed is used to refer to data which have
-undergone the process of decompression.
+LANGUAGE NOTE: Uncompressed = not compressed = plain data; it may never have
+been compressed. Decompressed is used to refer to data which have undergone
+the process of decompression.
-Copyright (C) 2009-2019 Antonio Diaz Diaz.
+Copyright (C) 2009-2021 Antonio Diaz Diaz.
This file is free documentation: you have unlimited permission to copy,
-distribute and modify it.
+distribute, and modify it.
The file Makefile.in is a data file used by configure to produce the
Makefile. It has the same copyright owner and permissions that configure