In computing, ".bak" is a
filename extension commonly used to signify a
backup copy of a
file.
When a program is about to overwrite an existing file (for example, when the user saves the document they are working on), the program may first make a copy of the existing file, with
.bak appended to the filename. This common
.bak naming scheme makes it possible to retrieve the original contents of the file in case of a failed write that corrupts the file, which could be caused by an
operating system crash, power outage, or disk space exhaustion.
Without the backup file, an unsuccessful write event may truncate a file, meaning it cuts off the file at a position, or leaves a blank file. In practice, this could cause a written document to become incomplete or get lost, a multimedia project file (e.g. from a video editor) to become unparseable, and user preferences being reset to default.
In a similar manner, a user may also manually make a copy of the file before the change and append
.bak to the filename, or alternatively save revisions into separate files, to facilitate reverting to an earlier revision in case of an error.
Other naming schemes are also in widespread use:
file~,
file.orig,
file.old, and appended time stamps.
Database Applications like
FoxPro and SQL Server use
.bak files to back up their databases and other applications, like
XML shell, create
.bak files in their
autosave process.
They do not get automatically deleted, so they need to be manually deleted after the process using it is stopped.
Example applications using .bak files
This is a partial list of applications that generate
.bak files (in some cases as an optional configuration setting):
*
Apophysis7X
*
Alteryx
Alteryx is an American computer software company based in Irvine, California, with a development center in Broomfield, Colorado. The company's products are used for data science and analytics. The software is designed to make advanced analytic ...
*
Aspell
GNU Aspell, usually called just Aspell, is a free software spell checker designed to replace Ispell. It is the standard spell checker for the GNU operating system. It also compiles for other Unix-like operating systems and Windows. The main pro ...
*
Audacity
*
AutoCAD
*
fluidsim
*
Blue Griffon
*
Captivate
Adobe Captivate is an authoring tool that is used for creating eLearning content such as software demonstrations, software simulations, branched scenarios, and randomized quizzes in Shockwave Flash ( .swf, a.k.a. ‘Small Web Format’) and HTML ...
*
Cubase
*
DraftSight
*
DrRacket
Racket is a general-purpose, multi-paradigm programming language and a multi-platform distribution that includes the Racket language, compiler, large standard library, IDE, development tools, and a set of additional languages including Typed Ra ...
*
Exiled Kingdoms rpg
*
Family Tree Maker
Family Tree Maker is genealogy software for Windows and Mac that allows the researcher to keep track of information collected during research and to create reports, charts, and books containing that information. The software was originally develo ...
*
Finale Notepad
*
FoxPro
*
FormZ
*
Google Chrome
Google Chrome is a cross-platform web browser developed by Google. It was first released in 2008 for Microsoft Windows, built with free software components from Apple WebKit and Mozilla Firefox. Versions were later released for Linux, macOS ...
*
Grand Theft Auto V
''Grand Theft Auto V'' is a 2013 action-adventure game developed by Rockstar North and published by Rockstar Games. It is the seventh main entry in the Grand Theft Auto, ''Grand Theft Auto'' series, following 2008's ''Grand Theft Auto IV'', and ...
*
HxD
HxD is a hex editor, disk editor, and memory editor developed by Maël Hörz for Windows. It can open files larger than 4 GiB and open and edit the raw contents of disk drives, as well as display and edit the memory used by running processes. ...
*
HyperCam
HyperCam is a screencasting program made and created by Hyperionics and Solveig Multimedia. It captures the action from a Microsoft Windows screen and saves it to an AVI (Audio Video Interleaved) or WMV (Windows Media Video) or ASF (Advanced Syste ...
*
JavaFX Scene Builder
*
Lazarus
*
LMMS
*
MATLAB
*
Minitab
*
Mozilla Firefox
Mozilla Firefox, or simply Firefox, is a free and open-source web browser developed by the Mozilla Foundation and its subsidiary, the Mozilla Corporation. It uses the Gecko rendering engine to display web pages, which implements current and a ...
*
Mupen64
Mupen64Plus, formerly named ''Mupen64-64bit'' and ''Mupen64-amd64'', is a free and open-source, cross-platform Nintendo 64 emulator, written in the programming languages C and C++. It allows users to play Nintendo 64 games on a computer by readin ...
*
Notepad++
Notepad++ is a text and source code editor for use with Microsoft Windows. It supports tabbed editing, which allows working with multiple open files in a single window. The product's name comes from the C postfix increment operator.
Notepad++ ...
*
NUPS
*
Opera
*
Outlook Express
*
Password Safe
Password Safe is a free and open-source password manager program originally written for Microsoft Windows but supporting wide area of operating systems with compatible clients available for Linux, FreeBSD, Android, IOS, BlackBerry and other o ...
(.ibak)
*
Photoshop
*
PScad
*
Free Pascal
*
Rhinoceros 3D
*
Sony Vegas
*
SQL Server
*
SCIA Engineer
*
Steinberg Cubase
Cubase is a digital audio workstation (DAW) developed by Steinberg for music and MIDI recording, arranging and editing. The first version, which was originally only a MIDI sequencer and ran on the Atari ST computer, was released in 1989. Cut-dow ...
*
Starbound
''Starbound'' is an action-adventure video game developed and published by Chucklefish. ''Starbound'' takes place in a two-dimensional, procedurally generated universe which the player is able to explore in order to obtain new weapons, armor, ...
*
TeamViewer Manager
*
Terraria
*
Texmaker
*
TextCrawler
*
Turing
*
Turbo C++
Turbo C++ is a discontinued C++ compiler and integrated development environment originally from Borland. It was designed as a home and hobbyist counterpart for Borland C++. As the developer focused more on professional programming tools, later T ...
*
UltraEdit
UltraEdit is a commercial text editor for Microsoft Windows, Linux and OS X created in 1994 by the founder of IDM Computer Solutions Inc., Ian D. Mead, and owned by Idera, Inc. since August 2021. The editor contains tools for programmers, includi ...
*
VEE
*
WhatsApp
*
Windows (BOOTSECT.BAK)
*
WinMerge
WinMerge is a free software tool for data comparison and merging of text-like files. It is useful for determining what has changed between versions, and then merging changes between versions.
For a planned development of version 3.x no com ...
*
Word
*
Zmodeler
''ZModeler'' (or ''Zanoza Modeler'') is a 3D modeling application developed by Oleg Melashenko. It is aimed at modelers who model vehicles and other objects for computer games such as Euro Truck Simulator, UK Truck Simulator, American Truck Simula ...
*
OpenMPT
External links
BAK file*
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References
Filename extensions
{{computing-stub