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• 7-zip
7-Zip is an open-source file archiver, an application used primarily to compress files. 7-Zip uses
its own 7z archive format, but can read and write several other archive formats. By default, 7-Zip
creates 7z-format archives with a .7z file extension. Each archive can contain multiple directories
and files. As a container format, security or size reduction are achieved using a stacked
combination of filters.
List of the most commons arguments:
7z:
name of executable
x:
use the extract command
a:
add to archive command
-r:
recourse all child directories
t:
test the specified archive
e:
use extract with full path command
u:
update command
d:
delete files
Compression algorithms
The following compression algorithms are currently defined:
LZMA – A variation of the LZ77 algorithm, using a sliding dictionary up to 4 GB in length for
duplicate string elimination. The LZ stage is followed by entropy coding using a Markov chainbased range coder and binary trees.
LZMA2 – modified version of LZMA providing better multithreading support and less
expansion of incompressible data.
Bzip2 – The standard Burrows–Wheeler transform algorithm. Bzip2 uses two reversible
transformations; BWT, then Move to front with Huffman coding for symbol reduction (the actual
compression element).
PPMd – Dmitry Shkarin's 2002 PPMdH (PPMII/cPPMII) with small changes: PPMII is an
improved version of the 1984 PPM compression algorithm (prediction by partial matching).
DEFLATE – Standard algorithm based on 32 kB LZ77 and Huffman coding. Deflate is found in
several file formats including ZIP, gzip, PNG and PDF. 7-Zip contains a from-scratch
DEFLATE encoder that frequently beats the de facto standard zlib version in compression size,
but at the expense of CPU usage.
• Gzip
Gzip is a file format and a software application used for file compression and decompression. is
based on the DEFLATE algorithm, which is a combination of LZ77 and Huffman coding.
DEFLATE was intended as a replacement for LZW and other patent-encumbered data
compression algorithms which, at the time, limited the usability of compress and other popular
archivers.
List of the most commons arguments:
✓ -c, --stdout
write on standard output, keep original files unchanged
✓ -d, --decompress
decompress
✓ -f, --force
force overwrite of output file and compress links
✓ -h, --help
give this help
✓ -k, --keep
keep (don't delete) input files
✓ -l, --list
list compressed file contents
✓ -L, --license
display software license
✓ -n, --no-name
do not save or restore the original name and time stamp
✓ -N, --name
save or restore the original name and time stamp
✓ -q, --quiet
suppress all warnings
✓ -r, --recursive
operate recursively on directories
--rsyncable
make rsync-friendly archive
✓ -S, --suffix=SUF
use suffix SUF on compressed files
✓ -t, --test
test compressed file integrity
✓ -v, --verbose
verbose mode
✓ -V, --version
display version number
✓ -1, --fast
compress faster
✓ -9, --best
compress better
Compression algorithms
The deflation algorithm used by gzip (also zip and zlib) is a variation of LZ77. It finds duplicated
strings in the input data. The second occurrence of a string is replaced by a pointer to the
previous string, in the form of a pair (distance, length). Distances are limited to 32K bytes, and
lengths are limited to 258 bytes.
• Rar
RAR is a proprietary archive file format that supports data compression, error recovery and file
spanning. are based on lossless compression. RAR remove the redundant information when you
compress (or “zip”) the file and restore it when you uncompress (or “unzip”)...