Archive file
In computing, an archive file is a computer file that is composed of one or more files along with metadata. Many archive formats also support compression of member files. Archive files are used to collect multiple data files together into a single file for easier portability and storage, or simply to compress files to use less storage space. Archive files often store directory structures, error detection and correction information, comments, and some use built-in encryption.[1][2][3]
Applications
Portability
Archive files are particularly useful in that they store file system data and metadata within the contents of a particular file, and thus can be stored on systems or sent over channels that do not support the file system in question, only file contents – examples include sending a directory structure over email, files with names unsupported on the target file system due to length or characters, and retaining files' date and time information.[4]
A single archive file may contain multiple member files; this can speed
in addition to gains due to compression.Software distribution
Beyond archival purposes, archive files are frequently used for packaging software for
Features
Features supported by various kinds of archives include:
- converting metadata into data stored inside a file (e.g., file name, permissions, etc.)
- checksums to detect errors
- data compression
- file concatenation to store multiple files in a single file
- file patches / updates (when recording changes since a previous archive)
- encryption
- error correction code to fix errors
- splitting a large file into many equal sized files for storage or transmission
Some archive programs have self-extraction, self-installation, source volume and medium information, and package notes/description.
The
Archive formats
An archive format is the file format of an archive file. Some formats are well-defined by their authors and have become conventions supported by multiple vendors and communities.[9]
Types
- Archiving only formats store concatenatefiles.
- Compression only formats only compress files.
- Multi-function formats can store metadata, concatenate, compress, encrypt, create error detection and recovery information, and package the archive into self-extracting and self-expanding files.
- Software packaging formats are used to create software packagesthat may be self-installing files.
- Disk image formats are used to create disk images of mass storage volumes.
Examples
Java also introduced a whole family of archive extensions such as jar and war (j is for Java and w is for web). They are used to exchange entire byte-code deployment. Sometimes they are also used to exchange source code and other text, HTML and XML files. By default they are all compressed.[11]
Error detection and recovery
Archive files often include
Archive files that do not natively support recovery records can use separate parchive (PAR) files that allows for additional error correction and recovery of missing files in a multi-file archive.[13]
See also
- File archiver
- Disk image
- Digital container format, a similar concept in media files
References
- ^ "Archive File: What it's Used For". Lifewire. Retrieved 2022-06-17.
- ^ "Archive files". www.ibm.com. 2015-02-07. Retrieved 2022-06-17.
- ^ "What is Archiving And Why is it Important?". Secure Data MGT. 2015-03-23. Retrieved 2022-06-17.
- Archive.org. p. 22. Retrieved June 17, 2022.
- ^ "Why file transfer speeds of small vs large files could be different". NetApp Knowledge Base. 2020-06-17. Retrieved 2022-06-17.
- ^ "Why Small Files Take Longer to Copy Than Large Files". Dataquest. 2018-10-10. Retrieved 2022-06-17.
- ^ Manager, Amit Ashbel, Senior Marketing and Strategy. "Data Archiving: The Basics and 5 Best Practices". cloud.netapp.com. Retrieved 2022-06-17.
{{cite web}}
: CS1 maint: multiple names: authors list (link) - ^ "What Is a File Extension & Why Are They Important?". Lifewire. Retrieved 2022-06-17.
- ^ "What are Archive Files?". www.exefiles.com. Retrieved 2022-06-17.
- ^ "Common file name extensions in Windows". support.microsoft.com. Retrieved 2022-06-17.
- ^ Malefanem, Moses. "Learning Java Network Programming".
{{cite journal}}
: Cite journal requires|journal=
(help) - ^ Drummond, James R. (1997). Parity, Checksums and CRC Checks (PDF) (1st ed.). Toronto. p. 13.
{{cite book}}
: CS1 maint: location missing publisher (link) - ^ text. "What are PAR and PAR2 Files?". Easynews. Retrieved 2022-06-17.
- "Application Note on the .ZIP file format"- official white paper published by PKWARE, Inc.
- Tape Archive (.TAR) file format specification- excerpt from File Format List 2.0 by Max Maischein
- "IBM 726 Magnetic tape reader/recorder from IBM Archives
- "1401 Data Processing System" from IBM Archives
External links
- File Archive formats at Curlie