Archive file

Short description: File with the content of other files plus associated metadata

An archive file stores the content of one or more computer files, possibly compressed and/or encrypted, with associated metadata such as file name, directory structure, error detection and correction information, and commentary. An archive file is often used to facilitate portability, distribution and backup, and to reduce storage use.[1][2][3] An archive file is usually generated and modified via a file archiver utility.

## Contents

* 1 Applications
* 1.1 Portability
* 1.2 Software distribution
* 2 Features
* 2.1 Error detection and recovery
* 3 Format
* 4 See also
* 5 References
* 6 External links

## Applications

### Portability

As an archive file stores file system information, including file content and metadata, it can be leveraged for file system content portability across heterogeneous systems. For example, a directory tree can be sent via email, files with unsupported names on the target system can be renamed during extraction, timestamps can be retained rather than lost during data transmission.[4] Also, transfer of a single archive file may be faster than processing multiple files due to per-file overhead,[5][6] and even faster if compressed.

### Software distribution

Beyond archiving, archive files are often used for software distribution. When used in connection with a package manager, an archive must conform to a package format and is called a package. In particular, the format usually requires a manifest file.[7] Examples include deb for Debian, JAR for Java, APK for Android, and self-extracting Windows Installer executables.

## Features

Notable features supported for various archives include:

* Concatenate multiple files in a single file
* Store file metadata as data, including file name, timestamps, permissions, source storage, notes and description
* Compression
* Encryption
* Error detection via checksums
* Error correction code to fix errors
* Splitting a large file into multiple, smaller files
* File patches/updates (when recording changes since a previous archive)
* Self-extraction
* Self-installation

### Error detection and recovery

Archive files often include parity checks and other checksums for error detection, for instance zip files use a cyclic redundancy check (CRC). RAR archives may include additional error correction data (called recovery records).[8]

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.[9]

## Format

Some archive file formats are well-defined and some have become conventions supported by multiple vendors and communities.[10] As is common for all files, the format of an archive is generally indicated by file name extension and/or file header.[11]

Commonly used formats include zip, rar, 7z, and tar.[12] Java introduced archive formats including jar (j for Java) and war (w for web) that store an entire runnable deployment; usually compressed.[13]

## See also

* Comparison of archive formats
* Digital container format
* Disk image - Computer file consisting of the contents of a storage device
* List of archive formats

## References

1. ↑ "Archive File: What it's Used For" (in en). https://www.lifewire.com/what-is-an-archive-file-2625792.
2. ↑ "Archive files" (in en-us). 2015-02-07. https://www.ibm.com/docs/en/zos/2.1.0?topic=routine-archive-files.
3. ↑ "What is Archiving And Why is it Important?" (in en). 2015-03-23. https://www.securedatamgt.com/blog/what-is-archiving/.
4. ↑ "Data Portability and Platform Competition | Is User Data Exported From Facebook Actually Useful to Competitors?". pp. 22. https://archive.org/details/data_portability_and_platform_competition_-_is_user_data_exported_from_facebook_.
5. ↑ "Why file transfer speeds of small vs large files could be different" (in en). 2020-06-17. https://kb.netapp.com/Advice_and_Troubleshooting/Data_Storage_Software/ONTAP_OS/Why_file_transfer_speeds_of_small_vs_large_files_could_be_different.
6. ↑ "Why Small Files Take Longer to Copy Than Large Files" (in en-GB). 2018-10-10. https://www.dq-int.co.uk/blog/why-small-files-take-longer-to-copy-than-large-files/.
7. ↑ Ashbel, Amit. "Data Archiving: The Basics and 5 Best Practices" (in en-us). https://cloud.netapp.com/blog/clc-blg-data-archiving-the-basics-and-5-best-practices.
8. ↑ Drummond, James R. (1997) (in En). Parity, Checksums and CRC Checks (1st ed.). Toronto. pp. 13. https://faraday.physics.utoronto.ca/PVB/Drummond/Micro/ln_comm1.pdf. Retrieved 2022-06-17.
9. ↑ text. "What are PAR and PAR2 Files?" (in en). https://help.easynews.com/kb/article/72-what-are-par-and-par2-files/.
10. ↑ "What are Archive Files?". https://www.exefiles.com/en/extensions/file-types/archive/.
11. ↑ "What Is a File Extension & Why Are They Important?" (in en). https://www.lifewire.com/what-is-a-file-extension-2625879.
12. ↑ "Common file name extensions in Windows". https://support.microsoft.com/en-us/windows/common-file-name-extensions-in-windows-da4a4430-8e76-89c5-59f7-1cdbbc75cb01.
13. ↑ Malefanem, Moses. "Learning Java Network Programming". https://www.academia.edu/21445522.

* "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

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