Zip file format is a data compression and archive format. A Zip file contains one or more files that have been compressed to reduce file size, or stored as-is. The process of compressing the document(s) into a Zip file is also known as deep-packing. The Zip file format permits a number of compression algorithms, but as of 2009, only Deflate is widely used and supported.
Zip is a simple archive format that compresses every file separately. Compressing files separately allows for individual files to be retrieved without reading through
other data; in theory, it may allow better compression by using different algorithms for different files.
A caveat to this is that archives containing a large number of small files end up
significantly larger than if they were compressed as a single
file (the classic example of the latter is the common tar.gz archive which consists of
a TAR archive compressed using gzip).
The format was originally created in 1989 by Phil Katz for PKZIP, and evolved from the previous ARC compression format by Thom Henderson. However, many software utilities other than PKZIP itself are now available to create, modify, or open (unzip, decompress) Zip files .
Zip files generally use the file extensions ".zip" or ".ZIP" and the MIME media type application/zip. Some software uses the ZIP file format as a wrapper for a large number of
small items in a specific structure; when this is done a different file extension is usually used.
The specification for Zip indicates that files can be stored either uncompressed or
using a variety of compression algorithms, but Zip is generally used with Katz's
DEFLATE algorithm, except when files being added are already compressed or are resistant to compression.
The Zip file contents are files and directories which are stored in arbitrary order. The location of a file is indicated in the so called central directory which is located at the end of the Zip file. The files and directories are represented by file entries.
Besides the file data each file entry is introduced by a local header with information about the file such as the comment, file size and file name. The central directory consists of file headers holding the relative offset of the local headers for each file.
Due to the arbitrary order and the fact that the order of the file entries
and the corresponding header references in the central directory may be different,
the format is non-sequential.
Using WinTar
WinTar is a simple and cute 32-bit Windows version tarball archiver - a powerful tool which allows Windows users to create, manage and extract most popular Unix/Linux tarball and windows CAB format archive files.
WinTar can create and read several different archive formats, including most popular tar variants, several cpio formats, and both BSD and GNU ar variants. It can also write shar archives and read ISO9660 CDROM images.
WinTar can create and read/extract Windows CAB archive files and ZIP files.
Introduction: http://www.miscosoftware.com/WinTar/wintar.htm
Download: http://www.miscosoftware.com/WinTar/store/WinTar.exe
Creating Zip Archive
When WinTar is running, it displays a list of files and folders in the current folder. Navigate to the folder that you want to add files and folders to the archive. After you select the files and folders and then do the following:
- Select menu File New archive and then select the archive file format from the popup menu, Zip File. or
- Click the main toolbar button New popup tag. When the popup menu displayed, select the Zip File.
These two methods will display the New Achive dialog. Navigate the folder you want to save the archive file, enter the archive file name in the File Name text box. At this point, you also have a chance to select the target archive format at the next Save File Type and Archive Format combo boxes. You may select the anyone compression method from the Compression combo Box, e.g. gzip,bzip2 except None or leave it as Using global options. Select None method, the archive will perform but do not apply compression, including Zip and CAB archive.
After click the OK button at the New Archive dialog, If you have selected files and/or folders on the first step, the Archive File Option dialog will display (the Globle Options controls this behavior).
After select some archive options and click OK button, the archive process starts.
Extracting Zip archive files
In order to extract Zip files using WinTar you must first open the required archive or select the archive file in File List pane window. This may be achieved in one of several ways:
- Target the archive file in the file list pane and select the archive file.
- Double-click or press Enter on the archive name in Windows shell (Explorer or Desktop). If WinTar was associated with archives, an archive will be opened in WinTar. You may associate WinTar with archives after installation using File Association dialog;
- Double-click or press Enter on the archive name in WinTar window;
- Run WinTar from the command line with a single parameter - the archive name.
If an archive is opened in WinTar, its contents are displayed. Select files and folders, which should be extracted. You may do this using Shift + arrow keys or Shift + left mouse button as in Windows Explorer and other Windows programs.
Having selected one or more files, select File Extract Archive menu or click Extract to button at the main toolbar, or press Alt+E , enter the destination folder in the dialog box and click on OK. This dialog box also offers a few advanced options for archive extraction.
After setting the advanced options, archive extrcting will start.Other Articles
Extracting files from ISO image file
Creating/Extracting CAB archive file
Creating Unix/Linux Shar archive files on Windows System
Creating Unix/Linux tar, tar.gz archive on Windows System
