Format Dmg

NOTE: The DMG format replaced the.IMG file format, which was previously used in Mac OS Classic. 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. How to Burn DMG to USB on Mac for Free (Disk Utility) The native disk image utility on Mac is ideal. ๐Ÿ”บ How to convert Image files to DMG? Choose files and upload them on the page. Select 'to DMG' and click 'Convert'. After a few seconds, you can download DMG files.

File TypeApple Disk Image

CategoryDisk Image Files

What is a DMG file?

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.

Today, software developers typically build and distribute applications for Mac users as DMG, .APP, or .PKG files. DMG files are especially common since their contents can be verified upon installation to ensure they have not been tampered with and they can also be compressed to reduce the size of the installer.

When a Mac user downloads a DMG file, he can simply double-click it to open it with the DiskImageMounter utility that comes with macOS. When the DMG file is opened, it mounts a virtual disk on the desktop and in an Apple Finder window as if it was a CD or a USB flash drive that was just inserted into the computer.

In the Finder window, the Mac user can double-click the program icon, which is an APP file, to run the app. Or the Mac user can drag the program icon to the 'Applications' folder icon to move it to the 'Applications' directory in macOS.

After the software stored in the DMG file is installed, the DMG file is no longer needed. Therefore, DMG files can be deleted after installing the software.

While DMG files are Mac-specific and not intended for use in Windows, there are several Windows programs that can extract their contents or convert them to other formats. Some programs include 7-Zip, PeaZip, and DMG2IMG.

NOTE: The DMG format replaced the .IMG file format, which was previously used in Mac OS Classic.

Open and view .DMG files with File Viewer Plus.Format dmg

Programs that open DMG files

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Updated 11/12/2019

Jul 19, 2015.dmg not recognized So, I've downloaded the.dmg file 3 times with Safari, tried Firefox and still no luck. This is an older MacBook with a fresh Lion install. Nov 12, 2019 While DMG files are Mac-specific and not intended for use in Windows, there are several Windows programs that can extract their contents or convert them to other formats. Some programs include 7-Zip, PeaZip, and DMG2IMG. NOTE: The DMG format replaced the.IMG file format, which was previously used in Mac OS Classic.

Apple Disk Image
The icon represents an internal hard drive within a generic file icon.
Filename extension.dmg, .smi, .img
Internet media typeapplication/x-apple-diskimage
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) and the New Disk Image Format (NDIF). An Apple disk image file's name usually has '.dmg' as its extension.

  • I'm trying to compile a c program and I am having some issues. In particular, when I use x8664-w64-mingw32-gcc as my compiler, it complains half way through my compilation saying 'tmp/src/libfas.
  • I'm not real sure what you are asking, so this is a guess on my part. Select any.dmg file. Press COMMAND-I to open the Get Info window. In the Open With panel use the dropdown menu to select DiskImageMounter then click on the Change All button. If DiskImageMounter is not displayed in the dropdown menu then select Other.
  • Nov 30, 2015 I googled this and it does seem like.dmg files not mounting is a problem sometimes with Snow Leopard. Only possible (but temporary) solution I saw that might work is to try to open the file with Disk Utility. Have you tried that?
  • Nov 18, 2019 A DMG file is 'mounted' as a drive and is treated by the operating system as if it were a physical hard drive, making it really easy to view its contents. The software you download for your Mac in a DMG format can be opened like any other file on a Mac, and then the setup program can be run to install the software.


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 multi-lingual 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. Flappy golf free online.

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', and are 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[8] (a spoonerism of FileVault).

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 trailer can be described using the following C structure.[10] All values are big-endian (PowerPC byte ordering) Os x mavericks dmg bootable usb windows.

The Specified File Is Not Recognized As Dmg Format In Word

Here is an explanation:

Position(in Hex)Length (in bytes)Description
0004Magic bytes ('koly').
0044File version (current is 4)
0084The length of this header, in bytes. Should be 512.
0188Data fork offset (usually 0, beginning of file)
0208Size of data fork (usually up to the XMLOffset, below)
0288Resource fork offset, if any
0308Resource fork length, if any
0384Segment number. Usually 1, may be 0
03C4Segment count. Usually 1, may be 0
04016128-bit GUID identifier of segment
0504Data fork checksum type
0544Data fork checksum size
058128Data fork checksum
0D88Offset of XML property list in DMG, from beginning
0E08Length of XML property list
0E8120Reserved bytes
1604Master checksum type
1644Master checksum size
168128Master checksum
1E84Unknown, commonly 1
1EC8Size of DMG when expanded, in sectors
1F412Reserved bytes (zeroes)


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. Currently, without additional tools, the resulting images may be mounted only under Mac OS X and under Linux (provided hfsplus support has been enabled). UDIF ADC-compressed images 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]
  • 7-Zip, including the free cross-platform port of its command-line interface, p7zip.

In Windows, most dmg images can be opened using several other programs such as UltraISO and IsoBuster. MacDrive can also mount simple dmg files as drives under windows, but not sparse disk or encrypted dmgs.[13] A free Apple DMG Disk Image Viewer also exists.[14]

In Linux and possibly other Unix flavors, most .dmg files can be burned to CD/DVD using any CD-burner program (using cdrecord directly or a front-end such as K3B or Brasero) or directly mounted to a mountpoint (e.g. mount -o loop,ro -t hfsplus imagefile.dmg /mnt/mountpoint).[15][16] darling-dmg is a FUSE module enabling easy DMG file mounting on Linux.[17]

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) โ€“ 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. ^'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. ^'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. ^Olivia Dehaviland (2015-03-03). 'Apple DMG Disk Image Viewer'. Archived from the original on 2015-04-02. Retrieved 2015-03-10.
  15. ^'How To Convert DMG To ISO in Windows, Linux & Mac'. Archived from the original on 2010-03-07.
  16. ^'Convert DMG To ISO using PowerISO'. Archived from the original on 2009-05-02. Retrieved 2009-02-15.
  17. ^'darling-dmg'. darling-dmg. Retrieved 29 March 2015.

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
Retrieved from ''
Internet media typeapplication/
Uniform Type Identifier (UTI)
Magic numberMSCF
Developed byMicrosoft
Type of formatArchive file format

Tdf File Format

Cabinet (or CAB) is an archive-file format for Microsoft Windows that supports lossless data compression and embedded digital certificates used for maintaining archive integrity. Cabinet files have .cabfilename extensions and are recognized by their first 4 bytes MSCF. Cabinet files were known originally as Diamond files.

The CAB file format may employ the following compression algorithms:

  • DEFLATE โ€“ invented by Phil Katz, the author of the ZIP file format
  • Quantum compression โ€“ licensed from David Stafford, the author of the Quantum archiver
  • LZX โ€“ invented by Jonathan Forbes and Tomi Poutanen, given to Microsoft when Forbes joined the company

A CAB archive can reserve empty spaces in the archive as well as for each file in the archive, for some application-specific uses like digital signatures or arbitrary data. A variety of Microsoft installation technologies use the CAB format - these include Windows Installer, Setup API, Device Installer and AdvPack (used by Internet Explorer to install ActiveX components). CAB files are also often associated[by whom?] with self-extracting programs like IExpress where the executable program extracts the associated CAB file. CAB files are also sometimes embedded into other files. For example, MSI and MSU files usually include one or more embedded CAB files.

File structure[edit]

A CAB archive can contain up to 65535 CAB-folders, (not to be confused with file system folders) each can contain up to 65535 files. Internally, each CAB-folder is treated as a single compressed block, which provides more efficient compression than individually compressing each file.

Every entry in a CAB-folder has to be a file.[1] Due to this structure, it is not possible to store empty folders in CAB archives.

The following shows an example a CAB file structure, demonstrating the relationship between CAB-folders and files:

CAB file
1st CAB-folder
Path: Records/Student_01.tsv
Path: Records/Photos/Student_01.jpg
2nd CAB-folder
Path: Records/Student_02.tsv
Path: Records/Photos/Student_02.jpg

Convert File Type

How paths should be handled is not specified in the CAB file format, leaving it to the software implementation.

  • Some affix file paths to filenames only, as if all files in a CAB archive are in a single folder. IExpress works this way, as does Microsoft Windows Explorer, which can open CAB archives as a folder.
  • Some can store the paths, and upon extraction, create folders as necessary. CABARC.EXE and EXTRACT.EXE (tools from Microsoft Cabinet SDK[2]) as well as lcab[3] and cabextract[4] (third-party open-source tools) work this way.
  • EXPAND.EXE, only since version 6 (which is included from Windows Vista to above) can extract files to their paths. The previous versions don't do it.[5]


The Specified File Is Not Recognized As Dmg Format In Windows 10

Microsoft Windows[edit]

makecab & expand
Operating systemMicrosoft Windows

Microsoft Windows supports extracting the contents of a CAB archive files using File Explorer, Setup API, and using the command-linecommandsexpand.exe and extract.exe.

The makecab.exe command is used to create CAB archives:

  • Compress a single file into a CAB archive

The Specified File (mbr) Is Not Recognized As Dmg Format

makecab.exe <input_file>[ <output_file>]
  • Read the diamond directive file (with .ddf filename extension) and create a CAB archive containing multiple files in a flat or hierarchical structure like a file system.

The Specified File Is Not Recognized As Dmg Format Download

makecab.exe /F <diamond_directive_file>[ <output_file>]

Third-party support[edit]

Other well-known software with CAB archive support includes WinZip, WinRAR or 7-Zip. However, fewer programs can create CAB archives. For a full list, see Comparison of file archivers ยง archive formats.

Related formats[edit]

The Specified File Is Not Recognized As Dmg Format In Excel

The .cab filename extension is also used by other installer programs (e.g. InstallShield) for their own proprietary archiving formats. InstallShield uses zlib for compression (see Deflate), but their headers are not the same as for Microsoft CAB files so they are incompatible and cannot be manipulated or edited with the programs that are made for standard Cabinet format. Specialized third-party utilities, such as Unshield,[6] can extract this specific proprietary format.


Microsoft Publisher has a 'Pack and Go' feature that bundles a publisher document, together with all external links, into a CAB file with a .PUZ extension. These files are meant to be activated with a companion .EXE file which is distributed along with the .PUZ file. These files may be opened with any CAB file extraction program.

The Specified File Is Not Recognized As Dmg Format In Pdf

Application in Component-Based Servicing and related bug[edit]

Windows (at least versions 7, 8, and 2008 R2 (on windows 10 at that location no cab are found)) uses the .cab format to archive its Component-Based Servicing (CBS) log, which is kept in the folder C:WindowsLogsCBS. A bug in the compression process can cause run-away generation of useless log files both in that folder and in C:WindowsTemp, which can consume disk storage until completely filling the hard drive.[7][8] Deletion of the files without following a specific procedure[8] can cause the deleted files to be regenerated at an increased pace.

See also[edit]

The Specified File Is Not Recognized As Dmg Format Free


Format Dmg

  1. ^ Microsoft Cabinet Format
  2. ^'Microsoft Cabinet Software Development Kit'. Support. Microsoft. Retrieved 27 March 2013.
  3. ^'lcab'. Freecode. Dice. Retrieved 27 March 2013.
  4. ^'cabextract'. Freecode. Dice. Retrieved 27 March 2013.
  5. ^'[Undocumented] [Bugs] Expand.exe (more about it) (Page 1) / Windows CMD Shell / SS64 Forum'. Retrieved 21 April 2018.
  6. ^'twogood/unshield'. GitHub. Retrieved 21 April 2018.
  7. ^'Clean Up Component-Based Servicing logs'. Microsoft TechNet. 7 July 2017.
  8. ^ abLeonhard, Woody (25 August 2016). 'Windows 7 log file compression bug can fill up your hard drive'. Computerworld. Retrieved 8 January 2019.

External links[edit]

The Specified File () Is Not Recognized As Dmg Format

  • Microsoft Cabinet SDK - updated versions of these resources are available in the Microsoft Windows SDK
  • Expand Command Reference - Windows XP Professional Product Documentation
  • Cabinet Software Development Kit (CAB SDK) - downloads of all Microsoft CAB SDK versions (free)

Format Disk In Drive D

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