lzip/clzip
1
0
Fork 0
Code Issues Activity

Merging upstream version 1.1~rc2.

Browse source 
Signed-off-by: Daniel Baumann <daniel@debian.org>
This commit is contained in:
Daniel Baumann 2025-02-17 19:14:54 +01:00
parent a8d17e4a46
commit 950a431716
Signed by: daniel
GPG key ID: FBB4F0E80A80222F
22 changed files with 1309 additions and 1071 deletions
Download patch file Download diff file Expand all files Collapse all files

168
doc/clzip.info
View file

@ -12,17 +12,17 @@ File: clzip.info, Node: Top, Next: Introduction, Up: (dir)
Clzip Manual
************
This manual is for Clzip (version 1.0, 5 April 2010).
This manual is for Clzip (version 1.1-rc2, 7 December 2010).
* Menu:
* Introduction:: Purpose and features of clzip
* Algorithm:: How clzip compresses the data
* Invoking Clzip:: Command line interface
* File Format:: Detailed format of the compressed file
* Examples:: A small tutorial with examples
* Problems:: Reporting bugs
* Concept Index:: Index of concepts
* Introduction:: Purpose and features of clzip
* Algorithm:: How clzip compresses the data
* Invoking Clzip:: Command line interface
* File Format:: Detailed format of the compressed file
* Examples:: A small tutorial with examples
* Problems:: Reporting bugs
* Concept Index:: Index of concepts
Copyright (C) 2010 Antonio Diaz Diaz.
@ -74,10 +74,12 @@ multivolume compressed tar archives.
or 2 times the dictionary size limit (1 if input file size is less than
dictionary size limit, else 2) plus 8 times the dictionary size really
used. For decompression it is a little more than the dictionary size
really used. Clzip will automatically use the smallest possible
dictionary size without exceeding the given limit. It is important to
appreciate that the decompression memory requirement is affected at
compression time by the choice of dictionary size limit.
really used.
Clzip will automatically use the smallest possible dictionary size
without exceeding the given limit. Keep in mind that the decompression
memory requirement is affected at compression time by the choice of
dictionary size limit.
When decompressing, clzip attempts to guess the name for the
decompressed file from that of the compressed file as follows:
@ -109,14 +111,12 @@ File: clzip.info, Node: Algorithm, Next: Invoking Clzip, Prev: Introduction,
***********
Clzip implements a simplified version of the LZMA (Lempel-Ziv-Markov
chain-Algorithm) algorithm. The original LZMA algorithm was designed by
Igor Pavlov.
The high compression of LZMA comes from combining two basic,
well-proven compression ideas: sliding dictionaries (LZ77/78) and
markov models (the thing used by every compression algorithm that uses
a range encoder or similar order-0 entropy coder as its last stage)
with segregation of contexts according to what the bits are used for.
chain-Algorithm) algorithm. The high compression of LZMA comes from
combining two basic, well-proven compression ideas: sliding dictionaries
(LZ77/78) and markov models (the thing used by every compression
algorithm that uses a range encoder or similar order-0 entropy coder as
its last stage) with segregation of contexts according to what the bits
are used for.
Clzip is a two stage compressor. The first stage is a Lempel-Ziv
coder, which reduces redundancy by translating chunks of data to their
@ -158,6 +158,13 @@ member or volume size limits are reached.
10) If there are more data to compress, go back to step 1.
The ideas embodied in clzip are due to (at least) the following people:
Abraham Lempel and Jacob Ziv (for the LZ algorithm), Andrey Markov (for
the definition of Markov chains), G.N.N. Martin (for the definition of
range encoding), Igor Pavlov (for putting all the above together in
LZMA), and Julian Seward (for bzip2's CLI and the idea of unzcrash).

File: clzip.info, Node: Invoking Clzip, Next: File Format, Prev: Algorithm, Up: Top
@ -170,49 +177,50 @@ The format for running clzip is:
Clzip supports the following options:
`--help'
`-h'
`--help'
Print an informative help message describing the options and exit.
`--version'
`-V'
`--version'
Print the version number of clzip on the standard output and exit.
`--member-size=SIZE'
`-b SIZE'
`--member-size=SIZE'
Produce a multimember file and set the member size limit to SIZE
bytes. Minimum member size limit is 100kB. Small member size may
degrade compression ratio, so use it only when needed. The default
is to produce single member files.
is to produce single-member files.
`--stdout'
`-c'
`--stdout'
Compress or decompress to standard output. Needed when reading
from a named pipe (fifo) or from a device. Use it to recover as
much of the uncompressed data as possible when decompressing a
corrupt file.
`--decompress'
`-d'
`--decompress'
Decompress.
`--force'
`-f'
`--force'
Force overwrite of output file.
`--keep'
`-k'
`--keep'
Keep (don't delete) input files during compression or
decompression.
`--match-length=LENGTH'
`-m LENGTH'
Set the match length limit in bytes. Valid values range from 5 to
273. Larger values usually give better compression ratios but
longer compression times.
`--match-length=LENGTH'
Set the match length limit in bytes. After a match this long is
found, the search is finished. Valid values range from 5 to 273.
Larger values usually give better compression ratios but longer
compression times.
`--output=FILE'
`-o FILE'
`--output=FILE'
When reading from standard input and `--stdout' has not been
specified, use `FILE' as the virtual name of the uncompressed
file. This produces a file named `FILE' when decompressing, a file
@ -220,20 +228,25 @@ The format for running clzip is:
`FILE00001.lz', `FILE00002.lz', etc, when compressing and
splitting the output in volumes.
`--quiet'
`-q'
`--quiet'
Quiet operation. Suppress all messages.
`--dictionary-size=SIZE'
`-s SIZE'
`--dictionary-size=SIZE'
Set the dictionary size limit in bytes. Valid values range from
4KiB to 512MiB. Clzip will use the smallest possible dictionary
size for each member without exceeding this limit. Note that
dictionary sizes are quantized. If the specified size does not
match one of the valid sizes, it will be rounded upwards.
`--volume-size=SIZE'
For maximum compression you should use a dictionary size limit as
large as possible, but keep in mind that the decompression memory
requirement is affected at compression time by the choice of
dictionary size limit.
`-S SIZE'
`--volume-size=SIZE'
Split the compressed output into several volume files with names
`original_name00001.lz', `original_name00002.lz', etc, and set the
volume size limit to SIZE bytes. Each volume is a complete, maybe
@ -241,15 +254,15 @@ The format for running clzip is:
volume size may degrade compression ratio, so use it only when
needed.
`--test'
`-t'
`--test'
Check integrity of the specified file(s), but don't decompress
them. This really performs a trial decompression and throws away
the result. Use `-tvv' or `-tvvv' to see information about the
file.
the result. Use it together with `-v' to see information about
the file.
`--verbose'
`-v'
`--verbose'
Verbose mode. Show the compression ratio for each file processed.
Further -v's increase the verbosity level.
@ -258,15 +271,21 @@ The format for running clzip is:
limit) as shown in the table below. Note that `-9' can be much
slower than `-1'. These options have no effect when decompressing.
The bidimensional parameter space of LZMA can't be mapped to a
linear scale optimal for all files. If your files are large, very
repetitive, etc, you may need to use the `--match-length' and
`--dictionary-size' options directly to achieve optimal
performance.
Level Dictionary size Match length limit
-1 1 MiB 10 bytes
-2 1.5 MiB 12 bytes
-3 2 MiB 17 bytes
-4 3 MiB 26 bytes
-5 4 MiB 44 bytes
-6 8 MiB 80 bytes
-7 16 MiB 108 bytes
-8 24 MiB 163 bytes
-1 1 MiB 5 bytes
-2 1.5 MiB 6 bytes
-3 2 MiB 8 bytes
-4 3 MiB 12 bytes
-5 4 MiB 20 bytes
-6 8 MiB 36 bytes
-7 16 MiB 68 bytes
-8 24 MiB 132 bytes
-9 32 MiB 273 bytes
`--fast'
@ -321,7 +340,7 @@ additional information before, between, or after them.
All multibyte values are stored in little endian order.
`ID string'
A four byte string, identifying the member type, with the value
A four byte string, identifying the lzip format, with the value
"LZIP".
`VN (version number, 1 byte)'
@ -358,9 +377,12 @@ File: clzip.info, Node: Examples, Next: Problems, Prev: File Format, Up: Top
5 A small tutorial with examples
********************************
WARNING! If your data is important, give the `--keep' option to clzip
and do not remove the original file until you verify the compressed
file with a command like `clzip -cd file.lz | cmp file -'.
WARNING! Even if clzip 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
`--keep' option to clzip and do not remove the original file until you
verify the compressed file with a command like
`clzip -cd file.lz | cmp file -'.
Example 1: Replace a regular file with its compressed version file.lz
@ -370,29 +392,47 @@ and show the compression ratio.
Example 2: Like example 1 but the created file.lz is multimember with a
member size of 1MiB.
member size of 1MiB. The compression ratio is not shown.
clzip -b 1MiB file
Example 3: Compress a whole floppy in /dev/fd0 and send the output to
Example 3: Restore a regular file from its compressed version file.lz.
If the operation is successful, file.lz is removed.
clzip -d file.lz
Example 4: Verify the integrity of the compressed file file.lz and show
status.
clzip -tv file.lz
Example 5: Compress a whole floppy in /dev/fd0 and send the output to
file.lz.
clzip -c /dev/fd0 > file.lz
Example 4: Create a multivolume compressed tar archive with a volume
Example 6: Decompress file.lz partially until 10KiB of decompressed data
are produced.
clzip -cd file.lz | dd bs=1024 count=10
Example 7: Create a multivolume compressed tar archive with a volume
size of 1440KiB.
tar -c some_directory | clzip -S 1440KiB -o volume_name
Example 5: Extract a multivolume compressed tar archive.
Example 8: Extract a multivolume compressed tar archive.
clzip -cd volume_name*.lz | tar -xf -
Example 6: Create a multivolume compressed backup of a big database file
Example 9: Create a multivolume compressed backup of a big database file
with a volume size of 650MB, where each volume is a multimember file
with a member size of 32MiB.
@ -437,12 +477,12 @@ Concept Index

Tag Table:
Node: Top226
Node: Introduction830
Node: Algorithm4377
Node: Invoking Clzip6608
Node: File Format10964
Node: Examples12920
Node: Problems14097
Node: Concept Index14623
Node: Introduction905
Node: Algorithm4439
Node: Invoking Clzip6963
Node: File Format11904
Node: Examples13860
Node: Problems15629
Node: Concept Index16155

End Tag Table