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authorDaniel Baumann <mail@daniel-baumann.ch>2015-11-07 15:35:26 +0000
committerDaniel Baumann <mail@daniel-baumann.ch>2015-11-07 15:35:26 +0000
commit391094ed961d742f431fdd89268274fc0bb52742 (patch)
tree2c77736ca41f43b00efe94400cfa5f9d9a431e76 /doc/plzip.texinfo
parentAdding debian version 1.0-2. (diff)
downloadplzip-391094ed961d742f431fdd89268274fc0bb52742.tar.xz
plzip-391094ed961d742f431fdd89268274fc0bb52742.zip
Merging upstream version 1.1~pre1.
Signed-off-by: Daniel Baumann <mail@daniel-baumann.ch>
Diffstat (limited to 'doc/plzip.texinfo')
-rw-r--r--doc/plzip.texinfo80
1 files changed, 44 insertions, 36 deletions
diff --git a/doc/plzip.texinfo b/doc/plzip.texinfo
index b832884..c3b0613 100644
--- a/doc/plzip.texinfo
+++ b/doc/plzip.texinfo
@@ -6,8 +6,8 @@
@finalout
@c %**end of header
-@set UPDATED 29 May 2013
-@set VERSION 1.0
+@set UPDATED 20 July 2013
+@set VERSION 1.1-pre1
@dircategory Data Compression
@direntry
@@ -36,11 +36,11 @@ This manual is for Plzip (version @value{VERSION}, @value{UPDATED}).
@menu
* Introduction:: Purpose and features of plzip
-* Program Design:: Internal structure of plzip
-* Invoking Plzip:: Command line interface
-* File Format:: Detailed format of the compressed file
+* Program design:: Internal structure of plzip
+* Invoking plzip:: Command line interface
+* File format:: Detailed format of the compressed file
* Problems:: Reporting bugs
-* Concept Index:: Index of concepts
+* Concept index:: Index of concepts
@end menu
@sp 1
@@ -55,21 +55,40 @@ to copy, distribute and modify it.
@cindex introduction
Plzip is a massively parallel (multi-threaded), lossless data compressor
-based on the lzlib compression library, with very safe integrity
-checking and a user interface similar to the one of bzip2, gzip or lzip.
+based on the lzlib compression library, with a user interface similar to
+the one of lzip, bzip2 or gzip.
-Plzip is intended for faster compression/decompression of big files on
-multiprocessor machines, which makes it specially well suited for
-distribution of big software files and large scale data archiving. On
-files big enough (several GB), plzip can use hundreds of processors.
-
-Plzip uses the lzip file format; the files produced by plzip are fully
-compatible with lzip-1.4 or newer, and can be rescued with lziprecover.
+Plzip can compress/decompress large files on multiprocessor machines
+much faster than lzip, at the cost of a slightly reduced compression
+ratio. On files large enough (several GB), plzip can use hundreds of
+processors. On files of only a few MB it is better to use lzip.
Plzip uses the same well-defined exit status values used by lzip and
bzip2, which makes it safer when used in pipes or scripts than
compressors returning ambiguous warning values, like gzip.
+Plzip uses the lzip file format; the files produced by plzip are fully
+compatible with lzip-1.4 or newer, and can be rescued with lziprecover.
+
+The lzip file format is designed for long-term data archiving and
+provides very safe integrity checking. The member trailer stores the
+32-bit CRC of the original data, the size of the original data and the
+size of the member. These values, together with the value remaining in
+the range decoder and the end-of-stream marker, provide a 4 factor
+integrity checking which guarantees that the decompressed version of the
+data is identical to the original. This guards against corruption of the
+compressed data, and against undetected bugs in plzip (hopefully very
+unlikely). The chances of data corruption going undetected are
+microscopic. Be aware, though, that the check occurs upon decompression,
+so it can only tell you that something is wrong. It can't help you
+recover the original uncompressed data.
+
+If you ever need to recover data from a damaged lzip file, try the
+lziprecover program. Lziprecover makes lzip files resistant to bit-flip
+(one of the most common forms of data corruption), and provides data
+recovery capabilities, including error-checked merging of damaged copies
+of a file.
+
Plzip replaces every file given in the command line with a compressed
version of itself, with the name "original_name.lz". Each compressed
file has the same modification date, permissions, and, when possible,
@@ -96,18 +115,6 @@ file from that of the compressed file as follows:
@item anyothername @tab becomes @tab anyothername.out
@end multitable
-As a self-check for your protection, plzip stores in the member trailer
-the 32-bit CRC of the original data, the size of the original data and
-the size of the member. These values, together with the value remaining
-in the range decoder and the end-of-stream marker, provide a very safe 4
-factor integrity checking which guarantees that the decompressed version
-of the data is identical to the original. This guards against corruption
-of the compressed data, and against undetected bugs in plzip (hopefully
-very unlikely). The chances of data corruption going undetected are
-microscopic. Be aware, though, that the check occurs upon decompression,
-so it can only tell you that something is wrong. It can't help you
-recover the original uncompressed data.
-
WARNING! Even if plzip is bug-free, other causes may result in a corrupt
compressed file (bugs in the system libraries, memory errors, etc).
Therefore, if the data you are going to compress is important, give the
@@ -116,8 +123,8 @@ you verify the compressed file with a command like
@w{@samp{plzip -cd file.lz | cmp file -}}.
-@node Program Design
-@chapter Program Design
+@node Program design
+@chapter Program design
@cindex program design
For each input file, a splitter thread and several worker threads are
@@ -138,8 +145,8 @@ large files with many members is only limited by the number of
processors available and by I/O speed.
-@node Invoking Plzip
-@chapter Invoking Plzip
+@node Invoking plzip
+@chapter Invoking plzip
@cindex invoking
@cindex options
@cindex usage
@@ -237,7 +244,8 @@ Use it together with @samp{-v} to see information about the file.
@item -v
@itemx --verbose
Verbose mode.@*
-When compressing, show the compression ratio for each file processed.@*
+When compressing, show the compression ratio for each file processed. A
+second -v shows the progress of compression.@*
When decompressing or testing, further -v's (up to 4) increase the
verbosity level, showing status, compression ratio, decompressed size,
and compressed size.
@@ -297,8 +305,8 @@ invalid input file, 3 for an internal consistency error (eg, bug) which
caused plzip to panic.
-@node File Format
-@chapter File Format
+@node File format
+@chapter File format
@cindex file format
Perfection is reached, not when there is no longer anything to add, but
@@ -387,8 +395,8 @@ If you find a bug in plzip, please send electronic mail to
find by running @w{@samp{plzip --version}}.
-@node Concept Index
-@unnumbered Concept Index
+@node Concept index
+@unnumbered Concept index
@printindex cp