In about times when volumes hard drives had ridiculous meanings, even the texts of the books when expanded seemed blasphemously huge. In fact, imagine a 40 MB hard drive, which also has Windows 3.1 (10 MB) and WinWord 6 (20 MB) installed. It was not surprising that this was the golden age of archivers, when dozens of their users knew not only by names and capabilities, but even by versions, not to mention dozens of keys, where “maximum compression” was welcomed.
It’s becoming sad now, and not because disk volumes have exceeded terabytes, but because users are still trying to compress many of the current data using archivers, without thinking at all about the rationality and purpose of this process. And very often it turns out very awkwardly.
Archivers, like all programs based on mathematical algorithms, cannot go beyond certain laws, including entropy, and only remove repetitive information from files. This is why you won’t be able to compress an already compressed file – it may even become larger in size. The only time re-compression can work is when a newer archiver is used, compressing an archive packed with an older version of the program. But this is rather an exception. It would be interesting to know what not to waste time on, because many of the files are hundreds of megabytes in size, and archiving and unpacking is a seriously long process even for modern computers.
Let's start with the popular one: there is no point in packing videos and music . With regard to video, you need to know that it is not only initially packed with powerful archiver codecs, but some data that is not essential for viewing has even been removed from it. By the way, they are encoded according to a similar scheme JPEG files, and therefore they cannot be compressed either. Music files, although compressed, may still make room on the disk a little more, but it makes no sense to fence the garden for the sake of 2-5%. In relation to pictures, you need to act according to the situation, but general principle This is - the more colors they have, the less chance there will be of compression. In general, pictures and photographs are a special case, since you can routinely sharply reduce their characteristics without losing quality when viewed on the target output device. Or do you really think you can distinguish between 4 billion colors? Rather, 256 adapted colors from the palette will be enough, and if you reduce the photo size and resolution, you can easily turn a 10-megabyte image into a 100-kilobyte one.
Programs and libraries are compressed rather weakly, given that in many cases they are initially compressed with dynamic codecs. Compression plays many roles here: protecting information, compression itself, obfuscating hackers from analysis, etc. And, besides, programs are usually distributed in compressed distributions, so there is no point in packaging them separately. As a result, disk images with programs and games. Save time – yours and others’...
Dozens of archivers are popular on the Internet today, and in the description of each program you can find that its algorithm is the very best... I decided to take several popular archivers on the Internet, namely: WinRar, WinUha, WinZip, KGB archiver, 7Z and test them in “combat” » conditions.
A little preface... The comparison may not be very objective. Comparison of ahivators was carried out on the most common home computer, the average for today. Besides, they didn’t take it various types data: compression comparison was carried out on a regular Word document, of which many who study or work with them can accumulate huge amount. Well, it is logical that it is advisable to pack information that you rarely use into an archive and sometimes extract it. And it’s much easier to transfer such a file: it will be copied to a flash drive faster than a bunch of small files, and it will be downloaded faster over the Internet...
Compression comparison table
For a small experiment, a relatively large RTF file- about 3.5 MB and compressed by different archivers. We are not taking into account the operating time yet, the features of the programs will be discussed further, but now we will just look at the compression level.
| Program | Format | Compression ratio | Size, kbytes | How many times has the file size decreased? ? |
| KGB Archiver 2 | .kgb | maximum | 141411 | 22,99 |
| WinRar | .rar | maximum | 190546 | 17,07 |
| WinUha | .uha | maximum | 214294 | 15,17 |
| 7Z | .7z | maximum | 218511 | 14,88 |
| WinZip | .zip | maximum | 299108 | 10,87 |
| Source file | .rtf | No compression | 3252107 | 1 |
As can be seen from the small plate, the highest compression ratio is achieved with the KGB Archiver 2 program - the original file size has decreased by 23 times! Those. if you have several gigabytes of various documentation on your hard drive that you don’t use and want to delete (but you can’t shake the feeling that it might come in handy) - wouldn’t it be easier to compress it with such a program and write it to disk...
But about all the pitfalls in order...
KGB Archiver 2
In general, it’s not a bad archiver; according to the developers, their compression algorithm is one of the “strongest”. It's hard to disagree...
Only the compression speed leaves much to be desired. For example, the file in the example (about 3 MB) was compressed by the program for about 3 minutes! It is not difficult to estimate that she will compress one CD disc for half a day, if not more.
But this is not particularly surprising. Unpacking a file takes as long as compression! Those. If you spent half a day compressing some of your documents, then you will spend the same amount of time getting them out of the archive.
Result: the program can be used for small amounts of information, especially when the minimum size of the source file is important (for example, the file needs to be placed on a floppy disk or on a small flash drive). But again, guess the size in advance compressed file You can’t, and perhaps you’ll waste your time on compression...
WinRar
The famous program in the post-Soviet space is installed on most computers. Probably, if she had not shown such good results, she would not have had so many fans. Below is a screenshot showing the compression settings, nothing special, except that the compression level was set to maximum.
Surprisingly, WinRar compressed the file in a few seconds, and the file size was reduced by 17 times. a very worthy result, considering that the time spent on processing is negligible. And the time to unpack the file is even less!
Result: great program, showing some of the best results. During the compression settings, you can also specify maximum size archive and the program will split it into several parts. This is very convenient for transferring a file from one computer to another on a flash drive or CD/DVD disk, when you cannot write the entire file to...
WinUha
A relatively young archivist. It cannot be called super-popular, but many users who often work with archives have an interest in it. And it is no coincidence, because according to the developers of the archiver, its compression algorithm is stronger than that of RAR and 7Z.
In our small experiment, I would not say that this is so. It is possible that on some other data it will show much better results...
By the way, when installing, select English language, in Russian - the program displays “kryakozabry”.
Result: a good program with an interesting compression algorithm. The time to process and create an archive is, of course, longer than WinRar, but for some types of data you can get a slightly higher compression ratio. Although, personally, I would not put much emphasis on this...
7Z
A very popular free archiver. Many argue that the compression ratio in 7z is even better than in WinRar. It is quite possible, but when compressed with the “Ultra” level on most files, it loses to WinRar.
Result: a good alternative to WinRar. Quite comparable compression ratio, good support Russian language, convenient integration into the Explorer context menu.
WinZip
Legendary, one of the most popular archivers ever. On the Internet, probably the most common archives are “ZIP”. And it’s no coincidence - despite the not-so-high compression ratio, the speed of operation is simply amazing. For example, Windows opens such archives as regular folders!
In addition, we should not forget that this archiver and compression format is much older than its newfangled competitors. And not everyone has them now powerful computers, which will allow you to quickly work with new formats. And the Zip format is supported by all modern archivers!
Hello, dear readers of the blog site. I am often asked which archiver compresses data better and what criteria should be used to choose it. I cannot answer which archiver compresses better, but I will conduct a small test to see which archiver has the highest compression ratio for different files.
The Winrar archiver has proven itself as best archiver on the Internet. However, its disadvantage is that it is shareware. After installation on your computer, it will work as a licensed product software within 40 days.
When this period ends, a message will appear indicating that you need to purchase a license for the software product. Fortunately, you can simply close this window and use the program as usual.
The developers of this program assume that after this period, if you do not like the program, you will delete it or refuse further use. The most interesting thing is that after the specified forty days, no restrictions are imposed on the program.
7-Zip is used by fewer users. This can be explained by the fact that it was developed later than Winrar, although it is in no way inferior in quality. Probably, users simply do not want to bother studying new program. The first release of 7-Zip occurred in 1999, and Winrar in 1995. The advantage of 7-Zip is that the program is distributed as a free software product.
So, today I will write a short report about the experiment. It all started with the fact that I took different files and compressed them with the two most popular archivers: Winrar and 7-Zip, which are often found on users’ computers.
After archiving, I looked at the degree of compression of these files, based on which I gave an assessment to each archiver.
The files that were archived are: text document with pictures, pdf file, music, video and installation file. I chose them based on a simple principle - I took what was most often found on the computer.
Typically, paid and free software differ in the number of functions and the quality of the tasks assigned to it. In this article we will find out which archiver compresses information better.
For clarity, I copied all the files into one folder. The compression method for Winrar was “Maximum”, and for 7-Zip “Ultra”. See the screenshot I took after the whole procedure below.
As I said above, to determine the winner, I compared the sizes of the compressed files. Where the size turned out to be smaller, that’s a plus. After this, a table was obtained, which can be viewed below.
| Files | Winrar | 7-Zip |
| + | ||
| Installation | + | |
| Video | + | |
| Music | + | |
| Text document | + |
As you can see, the score turned out to be 0:5 in favor of archiver 7 - Zip. To be honest, I myself did not expect that 7-Zip would win in all files.
For those who want to install the 7-Zip archiver for themselves, I give a link to the developers’ site, where you can download the latest version of the archiver. You can also download archiver 7 – Zip from my blog via a direct link.
In order to make sure that 7-Zip won, I archived all the files subject to archiving in advance into one common archive, and again it won. See screenshot below.
In this visual way, I answered users’ questions about which archiver compresses better. I for a long time enjoyed Winrar program, but after this test I additionally installed 7-Zip. I think that in cases where I need to compress information as much as possible, it will definitely be useful to me.
Each program has its own pros and cons, and you also need to understand that archivers may differ in functionality and intuitiveness of the interface. The choice of which program to use on your computer is yours. The most proven way to select programs is to install them on your computer.
I will publish an interesting article soon, so I’m not saying goodbye to you 😉 .
P.S. For the very beginners, watch the video:
Data compression is a procedure for recoding data performed in order to reduce its volume. Used for more rational use of data storage and transmission devices.
Compression can be lossless (when the original data can be restored without distortion) or lossy (recovery is possible with minor distortion). Lossless compression is used during processing computer programs and data, this is what is often called data archiving. Lossy compression is usually used to reduce the volume of audio, photo and video information; it is much more effective than lossless compression.
Compression is based on eliminating redundant information contained in the source data. The degree of redundancy depends on the type of data. For example, the degree of redundancy in video data is usually several times greater than that of graphic data, and the degree of redundancy in graphic data is several times greater than in text data. In addition, the degree of data redundancy depends on the coding system adopted.
An example of redundancy is the repetition of fragments (for example, words of natural or machine language) in the text. Such redundancy is usually eliminated by replacing the repeated sequence with a shorter value (code). Another type of redundancy is associated with the fact that some values in the compressed data occur more often than others, while it is possible to replace frequently occurring data with shorter codes, and rare ones with longer ones (probabilistic compression). Compression of data that does not have the property of redundancy (for example, a random signal or noise) is impossible.
Issues of data compression are quite acute in various fields of science and technology, wherever storage and transmission of information is required. Firstly, this is due to the cost of storage media, and secondly, with the need to transmit large flows of information over communication lines. In addition, data compression is inextricably linked with cryptography and the protection of information from accidental and intentional influence.
Programs that archive data are called archivers. In archivers, developers strive to improve two main parameters - compression ratio and speed. The operating speed is divided into two competing parameters - archiving speed and unarchiving speed. It is often not important how long we compress the data, but the time it takes to convert it back or vice versa is critical. Sometimes the amount of memory used is also important. The remaining properties are less significant and are usually not considered.
For these parameters, it is usually rarely possible to improve one thing without worsening the other. In addition, a compression algorithm that is optimal for some types of data may be completely unsuitable for others. For example, an archiver created to eliminate the redundancy of natural language texts and built on principles that allow achieving a high degree of compression of texts may not compress graphic data at all or even increase their volume.
In fact, researchers have scientifically proven theorems that impose restrictions on the degree of compression on archivers and on data compression itself.
1. For any data sequence, there is a theoretical compression limit that cannot be exceeded without losing some information.
2. For any compression algorithm, you can specify a data sequence for which this algorithm will not allow compression at all.
The ancestor of archivers in communications can be called Morse code, which contains a simple idea to increase communication speed - the more often a letter of the alphabet is used, the shorter its code should be. Subsequently, information compression algorithms began to be widely used in fax-modem and radio communications, allowing in both cases to increase the speed of information transfer.
The growing interest in archivers began with the advent of IBM-compatible personal computers. Before this, there were also compression programs, but they were known only to specialists and provided incomparably worse information compression performance.
Modern software tools for creating and maintaining archives are large functionality, many of which go far beyond simple data compression and effectively complement standard means operating system. In this sense, modern data archiving tools are called archive managers.
TO basic functions that most modern archive managers perform include:
extracting files from archives
creation of new archives
adding files to an existing archive
creating self-extracting archives
creation of distributed archives on media small capacity
testing the integrity of the archive structure
full or partial recovery of damaged archives
protection of archives from viewing and unauthorized modification.
creation of continuous (solid) archives
Self-extracting archives. In cases where archiving is carried out to transfer a document to the consumer, it should be ensured that he has the software necessary to extract source data from the compacted archive. If the consumer does not have such funds, self-extracting archives are created. A self-extracting archive is prepared on the basis of a regular archive by attaching a small software module. The archive itself receives a name extension.EXE, which is typical for executable files. The consumer will be able to launch it as a program, after which the archive will be unpacked on his computer automatically.
Distributed archives. In cases where transfer is intended large archive on small-capacity media, such as floppy disks, it is possible to distribute one archive in the form of small fragments on several media.
Archive protection. In most cases, archives are protected using a password, which is requested when you try to view, unpack or change the archive. Password protection is considered unsatisfactory and is not recommended for particularly sensitive information.
Continuous archives. A very large gain in size (10-50%), especially when archiving a large number of small files, is obtained when using the option to create continuous archives. In this case, all data will be archived as one large file, rather than each one separately. This significantly increases the efficiency of information compression, but this method has its drawbacks too. Firstly, it will take more time to unpack several files from such an archive than to extract from a regular one. Here it will matter which account was archived necessary files. If they were in the middle, then to unpack them the program will need to unpack all the packed files until it gets to the required ones. Creating archives in this way can also entail great losses, because if the archive turns out to be damaged, all the files that were in it will be lost. In the case of packaging in the usual way, it is possible to extract, if not all, but most of the files from the damaged archive.
TO additional functions archive managers include service functions that make work more convenient:
viewing files of various formats without extracting them from the archive
search for files and data inside archives
installing programs from archives without first unpacking
absence check computer viruses in the archive before it is unpacked
creating self-extracting multi-volume archives
selecting or adjusting the information compression ratio.
Different file formats are compressed with varying degrees of efficiency. Graphic files in *.bmp format (80-85%) and MS Office documents (on average 60%) are archived very well; Web pages are a little worse (40-50%). For executable files this figure varies (~50% depending on the archiver) and in most cases is quite low. Archiving has virtually no effect on the size of compressed files (graphics files in *.gif and *.jpg formats, DivX movies, CD images, etc.).
The most popular archivers among users are:
WinZip
WinRAR
7Zip
WinAce
PowerArchiver
WinZip
Cost: $7
Distribution size: 5929K
Manufacturer's website: http://www.winzip.com/
Supported formats: Cab, GZip, Tar, TGZ - file extraction only. Zip - full support.
Fixing corrupted archives: not supported.
Multi-volume archives: limited support.
The most common archive format is Zip, and the most common archiver is WinZip. The low compression ratio is compensated by the widespread popularity of WinZip.
Despite the fact that the compression ratio of the program is low, it has simple interface, as well as wizards for creating and unpacking archives. Zip archives may include comments and be encrypted using a password. Support for multi-volume archives in the Zip format itself is limited: they can only be created on floppy disks.
The standard version of WinZip can only create simple self-extracting (SFX) archives. To run the program after extracting files from the archive or change the text in the extractor window, you need to buy the WinZip Self-Extractor utility and pay another $49.
To increase the number of recognized archive formats, it is possible to connect Arj and Lha archivers. WinZip was one of the first GUI archivers for Windows and its excellent integration with Windows is still a benchmark. But on at the moment competing archivers have surpassed it both in terms of compression and user-friendliness of the interface.
WinRAR.
Cost: $29
Distribution size:1035K
Manufacturer's website: http://www.rarlab.com/
Supported formats: CAB, ARJ, LZH, TAR, GZip, ACE, UUE, BZ2, JAR, ISO, 7Z - file extraction only.
RAR, Zip - full support.
Fixing corrupted archives: supported for RAR and Zip formats.
Self-extracting archives: supported.
Encrypted archives: supported.
Eternal competitor WinZip programs. This archiver is especially loved by Russians, largely due to the fact that it was created by compatriot Leonid Roshal. On the world market software known as an archiver with one of the best data compression algorithms.
Restoring “damaged” archives is possible by default only for Zip archives. In order to minimize the likelihood of data loss, when creating WinRar archives, it is recommended to use the “Recovery Information” option (this checkbox can be found on the “General” tab of the archive creation window). If this has been done, then if the archive is damaged, it can be restored. In addition, in WinRar, you can reduce the likelihood of damage to the RAR archive by specifying the size of the recovery information when creating it. To do this, you need to run the command “Commands”> “Add recovery information” in the Winrar window. In this case, the volume of information for recovery cannot exceed ten percent of the total archive size.
Multi-volume archiving provided by the archiver is significantly more convenient than the floppy disk splitting method used in WinZip.
WinRAR understands almost all known archive formats. After installation, the program builds its main shortcuts into the main context menu, so you don’t have to go to the main menu every time and look for program shortcuts there, and then understand its interface. All main tasks are already in the context menu. Next to each item there is a well-recognized icon, so that when you open the menu, WinRAR shortcuts immediately catch your eye. When packing data, you can set the compression level of the archive or disable compression. In addition, the program allows you to protect archives with a password (you can also specify which files from the archive should be accessible, even if the user does not know the password), write comments, create self-extracting archives. WinRar has the ability to use a special multimedia compression algorithm that optimizes the compression of digitized audio and. graphic files.
For users who communicate with the archiver for the first time, special wizards are provided that will quickly bring them up to date. The program itself has a pleasant interface that does not cause any problems in learning.
7Zip
Cost: 0$
Distribution size: 837K
Manufacturer's website: http://www.7-zip.org/
Supported formats: RAR, CAB, ARJ, Z, CPIO, RPM, DEB, SPLIT - file extraction only.
ZIP, GZIP, TAR, BZIP2, 7Z - full support.
Fixing corrupted archives: not supported
Self-extracting archives: supported.
Encrypted archives: supported.
Continuous archives: supported.
Multi-volume archives: supported.
This is another archiver from Russian developers. Thanks to a more advanced compression algorithm, the quality of data archiving in our own *.7z format is superior even to WinRAR. True, this compression ratio is achieved due to the fact that the archiver works more slowly. Otherwise, 7-Zip really is superior in many ways to its more well-known competitors, and therefore more and more users are choosing it.
7-Zip's interface is ascetic, but we must not forget that the program is still at an early stage of development and is actively developing. The fact that the developer cares about distributing the product around the world is evidenced by the fact that the program supports a huge number of languages - in latest version there are more than sixty programs. Of course, there is also Russian.
7-Zip makes it possible to create password-protected archives, as well as encrypt the file names contained in the archives. This uses the 256-bit AES algorithm. It was this algorithm that was chosen in 2001 by the American National Institute of Standards and Technology (NIST) as a cryptographic standard for the near future, so we can say that this is one of the best encryption algorithms today.
The advantage of the program is that it is absolutely free, unlike its competitors, the author only asks to support the development by paying him a reward of $20.
WinAce
Cost: $29
Distribution size: 3801K
Manufacturer's website: http://www.winace.com/
Supported formats: ACE, ZIP, LHA, MS-CAB, ARC, ARJ, GZIP, TAR, BZip2, ISO, ZOO, RAR - file extraction only.
ACE, ZIP, LHA, MS-CAB, JAR - full support.
Fixing corrupted archives: supported for ACE and ZIP formats.
Self-extracting archives: supported.
Encrypted archives: supported.
Continuous archives: supported.
Multi-volume archives: supported.
Despite the fact that WinAce has been produced for quite a long time, the archiver has not been able to achieve such popularity among users as WinRar. In order for an archiver to compete with a competitor, it must surpass the competitor in two parameters - speed and compression ratio. The size of archives in the ACE format is often smaller than after using WinRar, but not so much as to attract attention. In addition, WinAce is not fast, spending almost twice as much time as WinRar. If we compare WinAce with 7Zip, then the main disadvantage of the archiver can be considered to be paid.
Another disadvantage of Winace is that the archiver is not highly stable, and as a result, from time to time the program window closes due to an “invalid operation.” This is a serious drawback, especially considering the almost trouble-free operation of Winrar and 7Zip.
To improve the compression of graphic and audio files, as well as executable (*.exe) files, the archiver implements additional multimedia compression algorithms, and delta compression for all other data types. It supports the creation of continuous archives, checking the integrity of all formats familiar to the program, restoring damaged ACE and ZIP archives, and much more. In addition, you can convert archives of various formats to ACE to reduce their size. The program has excellent integration with Windows.
PowerArchiver
Cost: $20
Distribution size: 3712K
Manufacturer's website: http://www.powerarchiver.com/
Supported formats: RAR, ARJ, ARC, ACE, ZOO, ISO, BIN, IMG, NRG - file extraction only.
ZIP, 7-ZIP, CAB, LHA (LZH), TAR, GZIP, BZIP2, BH - full support.
Fixing corrupted archives: supported for ZIP format.
Self-extracting archives: supported.
Encrypted archives: supported.
Continuous archives: not supported.
Multi-volume archives: supported.
PowerArchiver is a very powerful archiver. Beautiful, convenient and understandable interface. PowerArchiver, unlike WinRAR, 7Zip and WinAce, does not provide its own format for data compression; however, it supports a large number of different archives including RAR, ACE and 7-ZIP, and the latter is fully supported.
The built-in viewer allows you to “on the fly” view TXT, RTF and all popular graphic file formats directly in the archive. In addition, PowerArchiver offers the user 5 various methods encryption of highly sensitive data.
The rest of the set of functions is standard: converting various archives into those that are fully supported by the program, excellent integration with Windows, the ability to create multi-volume Zip archives and many others. The authors of the program are especially proud that it received a certificate from Microsoft as software optimized for Windows XP, with all the ensuing “consequences”, namely support for Windows XP themes. And PowerArchiver itself boasts a lot of its own skins, designed to completely change its appearance.
When archiving information, it is difficult to say with absolute certainty which of the archivers in this case will allow you to obtain the maximum compression ratio. It is most likely that out of the WinAce-WinRar-7Zip trio, WinRar will do a better job. However, even when compressing files of the same type (for example, the bmp graphic format), it is often impossible to determine in advance which of the archivers will compress the file better - any of the listed archivers can have the highest compression ratio. In most cases, the optimal compression format can only be determined empirically using optimization functions for specific type and the size of the compressed information. Therefore, if the size of the compressed file really matters, before sending the file by mail, placing it on an FTP server, or before burning it to a laser disk, it is best to compress the data with three archivers at once and see which one did the job better than the others.
List of used literature.
Fomin A.A. "Basics of Information Compression"
http://www.powerarchiver.com/
http://www.winace.com/
http://www.7-zip.org/
http://www.rarlab.com/
http://www.winzip.com/
http://ru.wikipedia.org/wiki/Archiving
http://256bit.ru/informat/index9.htm
http://www.computerra.ru/hitech/novat/26988/
One of the most common types system programs are programs designed for archiving, packaging files by compressing the information stored in them.
Information compression is the process of transforming information stored in a file, as a result of which its redundancy is reduced and, accordingly, less memory is required for storage.
Compression of information in files is carried out by eliminating redundancy in various ways, for example by simplifying the codes, eliminating constant bits from them, or representing repeating symbols or a repeating sequence of symbols in terms of a repetition factor and corresponding symbols. Various algorithms for such information compression are used.
Both one and several files can be compressed, which in compressed form are placed in the so-called archive file, or archive.
An archive file is a specially organized file containing one or more files in compressed or uncompressed form and official information about file names, date and time of their creation or modification, sizes, etc.
The purpose of file packaging is usually to ensure more compact placement of information on disk, reducing the time and, accordingly, the cost of transmitting information via communication channels to computer networks. In addition, packaging a group of files into one archive file significantly simplifies their transfer from one computer to another, reduces the time of copying files to disks, allows you to protect information from unauthorized access, and helps protect against infection by computer viruses.
Under compression ratio understand the ratio of the sizes of the compressed file and the original, expressed as a percentage.
Compression ratio depends on the compression program used, compression method, and source file type. Graphic image files are best compressed text files, data files, the compression ratio of which can reach 5 - 40%, files of executable programs and load modules are compressed less - 60 - 90%. Archive files are almost not compressed. Archiving programs differ in the compression methods they use, which consequently affects the compression ratio.
Archiving (packaging) - premises (loading) source files to an archive file in compressed or uncompressed form.
Unzipping (unpacking) is the process of restoring files from an archive exactly as they were before they were loaded into the archive. When unpacking, files are extracted from the archive and placed on disk or in RAM.
Programs that pack and unpack files are called archiver programs.
Large archive files can be placed on several disks (volumes). Such archives are called multi-volume. Tom is component multi-volume archive. By creating an archive from several parts, you can record its parts on several media.
Main types of archiver programs
Currently, several dozen archiver programs are used, which differ in the list of functions and operating parameters, but the best of them have approximately the same characteristics. Among the most popular programs are: Zip (and its modification WinZip), WinRAR, Arj (and its varieties), G-Zip, 7-Zip.
Archive programs also allow you to create archives that do not require any programs to extract files from, since the archive files themselves can contain an unpacking program. Such archive files are called self-extracting. A self-extracting archive file is a bootable, executable module that is capable of independently unzipping the files it contains without using an archiver program.
Self-extracting archive got the name SFX archive(SelF-eXtracting). Archives of this type are usually created in EXE file format.
Many archiver programs unpack files by dumping them onto disk, but there are also those that are designed to create a packaged executable module (program). As a result of such packaging, a program file is created with the same name and extension, which, when loaded into RAM, self-extracts and runs immediately. At the same time, the reverse transformation is also possible program file in unpacked format. Such archivers include programs Upx, PKLITE, LZEXE.
The EXPAND program, which is part of the operating utilities Windows systems, used to unpack files software products supplied by Microsoft.
Ways to manage the archiver program
The archiver program is controlled in one of the following ways:
- - by using command line, in which a launch command is generated containing the name of the archiver program, the control command and its configuration keys, as well as the names of the archive and source files;
- - using the built-in shell and dialog panels that appear after starting the program and allow control using menus and function keys, which creates more comfortable working conditions for the user;
- - by using context menu Conductor in operating system Windows.
