Dmg Extensiion


A DMG file is a mountable disk image used to distribute software to the macOS operating system. The file is typically downloaded from the Internet by a Mac user, then double-clicked to install an application on the computer. DMG Files are Mac-formatted Disk Image Files especially correlated with Macintosh OS X by Apple Inc.These files are mountable disk images that are used for installing any application on Mac computer, and it can consist of any type of file.

Dmg File Extension free download - Extension Changer, IceOp Camfrog Extension, File Shredder, and many more programs. DMG FAT & exFAT DMG UDF DMG HFS DMG HFS+ Bzip2 DMG Raw DMG Zlib DMG Zero DMG Encrypted 4GB+ DMGs OS X betas iOS IPSW files iOS IPA files What is the software for? Disk image files that are stored in the DMG file format and are appended with the.dmg extension are intended as virtual disks for Mac OS X platforms. These DMG files can be mounted unto a virtual drive or directly activated to launch the Apple Disk Utility program, in order to view and use the content of these.dmg files.

DMG may refer to:




  • Dames Making Games, a Canadian non-profit organization that encourages the participation of women, non-binary, femme and queer people in the creation of video games
  • Davidson Media Group, an American radio station holding company
  • Diamante Music Group, a former American music record label distributor
  • Disney Music Group, a record label group
  • DMG Entertainment, a Chinese-based film production and distribution company
  • DMG Nashville, a brand of Hollywood Records
  • DMG Radio Australia, owner of the Nova and Classic Rock radio networks
  • DMG TV, part of the British record label Demon Music Group

Other organizations[edit]

  • Daily Mail and General Trust, an international media company
  • Daimler Motoren Gesellschaft (now Daimler AG), an early German automobile manufacturer
  • Deckel Maho Gildemeister, earlier name of DMG Mori Aktiengesellschaft, a German engineering company
  • Deutsche Morgenländische Gesellschaft (German Oriental Society), organization that studies Asia and the Orient
  • District Management Group, an elite cadre of the Civil Service of Pakistan, now known as the Pakistan Administrative Service
  • DMG interpersonal, a club for Charities in Germany
  • DMG Media, a national newspaper and website publisher in the UK
  • DMG Mori Seiki Co., a Japanese tools manufacturing company
  • D.M.G. Grupo Holding S.A., a Colombian company disbanded under the suspicion of money laundering

Science and technology[edit]

Dmg Extensiion
  • Dimethylglycine, a derivative of the amino acid glycine
  • Dimethylglyoxime, an organic chemical used in analysis as a precipitant for palladium or nickel
  • Direct metalation group, the target of directed ortho metalation
  • Dot Matrix Game, the official product code for the original Game Boy handheld video game system
  • .dmg file, the Apple Disk Image, a file format used in the macOS computer operating system

Other uses[edit]

  • Decoration for Merit in Gold, a South African military decoration
  • DMG (rapper), a rapper from Saint Paul, Minnesota
  • DMG 90, an edition of the Holden Commodore
  • Dungeon Master's Guide, a rulebook for the game Dungeons & Dragons
  • ISO 639:dmg or Kinabatangan language, a language of Malaysia
  • Distinguished Master Guardian, Counter-Strike: Global Offensive competitive rank
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Apple Disk Image
The icon depicts an internal hard drive within a generic file icon.
Filename extension
Internet media type
Uniform Type Identifier (UTI)
Developed byApple Inc.
Type of formatDisk image

Apple Disk Image is a disk image format commonly used by the macOS operating system. When opened, an Apple Disk Image is mounted as a volume within the Macintosh Finder.

An Apple Disk Image can be structured according to one of several proprietary disk image formats, including the Universal Disk Image Format (UDIF) from Mac OS X and the New Disk Image Format (NDIF) from Mac OS 9. An Apple disk image file's name usually has '.dmg' as its extension. The macOS DMG is available online for free


Apple Disk Image files are published with a MIME type of application/x-apple-diskimage.

Different file systems can be contained inside these disk images, and there is also support for creating hybrid optical media images that contain multiple file systems.[1] Some of the file systems supported include Hierarchical File System (HFS), HFS Plus, File Allocation Table (FAT), ISO9660 and Universal Disk Format (UDF).[1][2]

Apple Disk Images can be created using utilities bundled with Mac OS X, specifically Disk Copy in Mac OS X v10.2 and earlier and Disk Utility in Mac OS X v10.3 and later. These utilities can also use Apple disk image files as images for burning CDs and DVDs. Disk image files may also be managed via the command line interface using the hdiutil utility.[3]


In Mac OS X v10.2.3, Apple introduced Compressed Disk Images[4] and Internet-Enabled Disk Images for use with the Apple utility Disk Copy, which was later integrated into Disk Utility in 10.3. The Disk Copy application had the ability to display a multilingual software license agreement before mounting a disk image. The image will not be mounted unless the user indicates agreement with the license.[5]

An Apple Disk Image allows secure password protection as well as file compression, and hence serves both security and file distribution functions; such a disk image is most commonly used to distribute software over the Internet.


Apple originally created its disk image formats because the resource fork used by Mac applications could not easily be transferred over mixed networks such as those that make up the Internet. Even as the use of resource forks declined with Mac OS X, disk images remained the standard software distribution format. Disk images allow the distributor to control the Finder's presentation of the window, which is commonly used to instruct the user to copy the application to the correct folder.

A previous version of the format, intended only for floppy disk images, is usually referred to as 'Disk Copy 4.2' format, after the version of the Disk Copy utility that was used to handle these images.[1] A similar format that supported compression of floppy disk images is called DART.[1][6]

New Disk Image Format (NDIF) was the previous default disk image format in Mac OS 9,[1] and disk images with this format generally have a .img (not to be confused with raw .img disk image files) or .smi file extension. Files with the .smi extension are actually applications that mount an embedded disk image, thus a 'Self Mounting Image', intended only for Mac OS 9 and earlier.[7][2]

Universal Disk Image Format (UDIF) is the native disk image format for Mac OS X. Disk images in this format typically have a .dmg extension.[1]

File format[edit]

Apple has not released any documentation on the format, but attempts to reverse engineer parts of the format have been successful. The encrypted layer was reverse engineered in an implementation called VileFault (a spoonerism of FileVault).[8]

Apple disk image files are essentially raw disk images (i.e. contain block data) with some added metadata, optionally with one or two layers applied that provide compression and encryption. In hdiutil, these layers are called CUDIFEncoding and CEncryptedEncoding.[1]

UDIF supports ADC (an old proprietary compression format by Apple), zlib, bzip2 (as of Mac OS X v10.4), and LZFSE (as of Mac OS X v10.11)[9] compression internally.


The UDIF metadata is found at the end of the disk image following the data. This trailer can be described using the following C structure.[10] All values are big-endian (PowerPC byte ordering)

The XML plist contains a blkx (blocks) key, with information about how the preceding data fork is allocated. Movies123 once upon a time... in hollywood 2019 full movie free. The main data is stored in a base64 block, using tables identified by the magic 'mish'. This 'mish' structure contains a table about blocks of data and the position and lengths of each 'chunk' (usually only one chunk, but compression will create more).[10] The data and resource fork information is probably inherited from NDIF.


The encryption layer comes in two versions. Version 1 has a trailer at the end of the file, while version 2 (default since OS X 10.5) puts it at the beginning. Whether the encryption is a layer outside of or inside of the blkx metadata (UDIF) is unclear from reverse engineered documentation, but judging from the vfcrack demonstration it's probably outside.[8]


There are few options available to extract files or mount the proprietary Apple Disk Image format. Some cross-platform conversion utilities are:

  • dmg2img was originally written in Perl; however, the Perl version is no longer maintained, and the project was rewritten in C. It extracts the raw disk image from a DMG, without handling the file system inside. UDIF ADC-compressed images (UDCO) have been supported since version 1.5.[11]
  • DMGEXtractor is written in Java with GUI, and it supports more advanced features of dmg including AES-128 encrypted images but not UDCO images.[12]
  • The Sleuth Kit. Handles the DMG format, HFS+, and APFS.

Most dmg files are unencrypted. Because the dmg metadata is found in the end, a program not understanding dmg files can nevertheless read it as if it was a normal disk image, as long as there is support for the file system inside. Tools with this sort of capacity include:

Dmg Extension File Mac

  • Cross-platform: 7-zip (HFS/HFS+), PeaZip (HFS/HFS+).
  • Windows: UltraISO, IsoBuster, MacDrive (HFS/HFS+).[13]
  • Unix-like: cdrecord and mount (e.g. mount -o loop,ro -t hfsplus imagefile.dmg /mnt/mountpoint).[14][15]

Tools with specific dmg support include:

Dmg Extension File

  • Windows:
    • Transmac can handle both UDIF dmgs and sparsebundles, as well as HFS/HFS+ and APFS. It is unknown whether it handles encryption.[16] It can be used to create bootable macOS installers under Windows.[17]
    • A free Apple DMG Disk Image Viewer also exists, but it is unknown how much what it actually supports.[18]
  • Unix-like:
    • darling-dmg is a FUSE module enabling easy DMG file mounting on Linux. It supports UDIF and HFS/HFS+.[19]

See also[edit]


  1. ^ abcdefg'hdiutil(1) Mac OS X Manual Page'. Archived from the original on 2016-05-14. Retrieved 2016-05-14.
  2. ^ ab'Mac OS X: Using Disk Copy disk image files'. Archived from the original on 2013-12-19. Retrieved 2013-04-25.
  3. ^hdiutil(1) – Darwin and macOS General Commands Manual
  4. ^'Re: Some apps refuse to launch in 10.2.8! (OT, but very important)'. Archived from the original on 2014-01-17.
  5. ^'Guides'. Apple. Archived from the original on 2009-03-06. Retrieved 2010-10-27.
  6. ^'DART 1.5.3: Version Change History'. Archived from the original on 2013-12-19. Retrieved 2013-04-25.
  7. ^'Software Downloads: Formats and Common Error Messages'. Archived from the original on 2010-12-24. Retrieved 2009-05-06.
  8. ^ ab'VileFault'. 2006-12-29. Archived from the original on 2007-01-09. Retrieved 2010-10-27.
  9. ^Michael Tsai (2015-10-07). 'LZFSE Disk Images in El Capitan'. Archived from the original on 2017-04-09. Retrieved 2017-04-09.
  10. ^ ab'Demystifying the DMG File Format'. Archived from the original on 2013-03-17.
  11. ^'dmg2img'. Archived from the original on 29 November 2010. Retrieved 2010-10-27.
  12. ^'DMGExtractor'. Archived from the original on 2011-01-02. Retrieved 2011-01-03.
  13. ^MacDrive Features / Boot Camp / System Requirements /. 'MacDrive Home page'. Mediafour. Archived from the original on 4 October 2010. Retrieved 2010-10-27.
  14. ^'How To Convert DMG To ISO in Windows, Linux & Mac'. Archived from the original on 2010-03-07.
  15. ^'Convert DMG To ISO using PowerISO'. Archived from the original on 2009-05-02. Retrieved 2009-02-15.
  16. ^'About TransMac for Windows'.
  17. ^'Convert'. winytips. Retrieved 5 May 2020.
  18. ^Olivia Dehaviland (2015-03-03). 'Apple DMG Disk Image Viewer'. Archived from the original on 2015-04-02. Retrieved 2015-03-10.
  19. ^'darling-dmg'. darling-dmg. Retrieved 29 March 2015.

Dmg Extension Name

External links[edit]

  • Apple Developer Connection A Quick Look at PackageMaker and Installer
  • O'Reilly Mac DevCenter Tip 16-5. Create a Disk Image from a Directory in the Terminal
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