What Is Disk-o.dmg
The icon represents an internal hard drive within a generic file icon. | |
| Filename extension | .dmg, .smi, .img |
|---|---|
| Internet media type | application/x-apple-diskimage |
| Uniform Type Identifier (UTI) | com.apple.disk-image |
| Developed by | Apple Inc. |
| Type of format | Disk image |
Nov 18, 2019 A DMG file is an Apple Disk Image file often used to store compressed software installers. You can open DMG files on Windows, Mac, and Linux. Qemu-kvm for illumos-kvm. Contribute to joyent/illumos-kvm-cmd development by creating an account on GitHub. 69 Outgoing links. These are links going to different origins than the main page. For each link, only the first name is shown. Part 1: How to Burn DMG to USB on Mac for Free (Disk Utility) The native disk image utility on Mac is ideal for burning a DMG to a USB drive. Once you burn the file to the drive, this drive can be used to install the associated application on any other Mac system.
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.
Features[edit]
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]
What Is Disk-o.dmg Used
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.
History[edit]
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.
What Is Disk-o.dmg Made
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.
Trailer[edit]
The trailer can be described using the following C structure.[10] All values are big-endian (PowerPC byte ordering)
Here is an explanation:
| Position(in Hex) | Length (in bytes) | Description |
|---|---|---|
| 000 | 4 | Magic bytes ('koly'). |
| 004 | 4 | File version (current is 4) |
| 008 | 4 | The length of this header, in bytes. Should be 512. |
| 00C | 4 | Flags. |
| 010 | 8 | Unknown. |
| 018 | 8 | Data fork offset (usually 0, beginning of file) |
| 020 | 8 | Size of data fork (usually up to the XMLOffset, below) |
| 028 | 8 | Resource fork offset, if any |
| 030 | 8 | Resource fork length, if any |
| 038 | 4 | Segment number. Usually 1, may be 0 |
| 03C | 4 | Segment count. Usually 1, may be 0 |
| 040 | 16 | 128-bit GUID identifier of segment |
| 050 | 4 | Data fork checksum type |
| 054 | 4 | Data fork checksum size |
| 058 | 128 | Data fork checksum |
| 0D8 | 8 | Offset of XML property list in DMG, from beginning |
| 0E0 | 8 | Length of XML property list |
| 0E8 | 120 | Reserved bytes |
| 160 | 4 | Master checksum type |
| 164 | 4 | Master checksum size |
| 168 | 128 | Master checksum |
| 1E8 | 4 | Unknown, commonly 1 |
| 1EC | 8 | Size of DMG when expanded, in sectors |
| 1F4 | 12 | Reserved bytes (zeroes) |
Utilities[edit]
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]
References[edit]
- ^ abcdefg'hdiutil(1) Mac OS X Manual Page'. Archived from the original on 2016-05-14. Retrieved 2016-05-14.
- ^ ab'Mac OS X: Using Disk Copy disk image files'. Archived from the original on 2013-12-19. Retrieved 2013-04-25.
- ^
hdiutil(1)– Darwin and macOS General Commands Manual - ^'Re: Some apps refuse to launch in 10.2.8! (OT, but very important)'. Archived from the original on 2014-01-17.
- ^'Guides'. Apple. Archived from the original on 2009-03-06. Retrieved 2010-10-27.
- ^'DART 1.5.3: Version Change History'. Archived from the original on 2013-12-19. Retrieved 2013-04-25.
- ^'Software Downloads: Formats and Common Error Messages'. Archived from the original on 2010-12-24. Retrieved 2009-05-06.
- ^'VileFault'. 2006-12-29. Archived from the original on 2007-01-09. Retrieved 2010-10-27.
- ^Michael Tsai (2015-10-07). 'LZFSE Disk Images in El Capitan'. Archived from the original on 2017-04-09. Retrieved 2017-04-09.
- ^'Demystifying the DMG File Format'. Archived from the original on 2013-03-17.
- ^'dmg2img'. Archived from the original on 29 November 2010. Retrieved 2010-10-27.
- ^'DMGExtractor'. Archived from the original on 2011-01-02. Retrieved 2011-01-03.
- ^MacDrive Features / Boot Camp / System Requirements /. 'MacDrive Home page'. Mediafour. Archived from the original on 4 October 2010. Retrieved 2010-10-27.
- ^Olivia Dehaviland (2015-03-03). 'Apple DMG Disk Image Viewer'. DataForensics.org. Archived from the original on 2015-04-02. Retrieved 2015-03-10.
- ^'How To Convert DMG To ISO in Windows, Linux & Mac'. Archived from the original on 2010-03-07.
- ^'Convert DMG To ISO using PowerISO'. Archived from the original on 2009-05-02. Retrieved 2009-02-15.
- ^'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
A DMG disk image file is Apple's container format for capturing entire drives or disks, similar to ISO for other platforms like Windows. It consists of data blocks that represent a physical disc. If you're on a Windows machine, you're limited in what you can do with DMG files. That's why you need third-party utilities to create a bootable DVD from DMG on Windows. This article explains two different methods to burn DMG files to amake bootable macOS installation DVD in Windows.
Method 1: How to Create Bootable DVD from DMG (Command Prompt)
This approach utilizes a tool called DMG2IMG, which converts DMG file into ISO, the universally more compatible archive format. This ISO file is then burned using a command line execution in Command Prompt. You don't really need any experience with disk images or command line work, but it will certainly help should something go wrong. If you're not comfortable with any of this, you can skip to Method 2, which showcases a powerful but user-friendly tool that does it all for you. But first, let's see how the Command Prompt method of creating a bootable DVD from DMG works.
Note: The older version of DMG2IMG is called DMG2ISO. Although the download is available in the link provided in Step 1 below, it is recommended that you use DMG2IMG instead. Why does buster shulk do more dmg in windows 7. The utility has the ability to convert DMG into both ISO and IMG, based on your needs.
Step 1. Install DMG2IMG on a Windows PC after downloading the zipped win32 binary from this website. Unzip the file and run the .exe to install the program. You can also download DMG2ISO, but DMG2IMG is the recommended software to use.
Step 2. Open Command Prompt on your PC and execute the following command to convert your DMG into ISO. Be sure to change the file names as appropriate, and include the whole file path from the main directory:
dmg2img.exe c:downloadsexample.dmg c:downloadsexampleconverted.iso
Step 3. Now that your ISO file is ready, you can use the Windows ISO burning utility or a free application like FreeISOBurner to create a bootable DVD.
This DVD can be used to install macOS in virtual Windows environments with tools like Virtualbox. You can't use ISO files to install software in Mac, so if this is intended for a computer running Mac OS X or macOS, you will need to convert it back to DMG before you can install the program in question. If you're not confident that you can carry out the steps properly, then continue to Method 2.
Method 2: How to Make a Bootable DVD for Mac on Windows (DMGGeeker)
Conversion processes aren't always accurate and success rate is low for the first method. Many DVD are not able to be used to install macOS due to boot errors. Although DMG2IMG is a great tool, you may find that your resulting ISO file is corrupted and therefore useless. That means doing it all over again. Instead, you can try using DMGGeeker, which allows you to directly burn DMG to a DVD in Windows without having to convert the file. Such a disk can be used to boot a Mac computer.
DMGGeeker is an emerging star in the world of disk image file management software. It allows you to edit, add files to, delete content from, rename and do a lot more with DMG files on Windows without any conversion necessary. If you've been searching for the ideal DMG handling tool for Windows, your search has just ended. Let's see how the process works for creating a bootable media from DMG in Windows. It works with all recent versions of Windows.
Step 1Prepare for Installation
You can download it from the official site here. And then install DMGGeeker on a Windows PC.
Step 2Open DMGGeeker in Windows
Launch the application and click on the 'Burn' option. You'll see the other tools available for DMG files.
Step 3Create Bootable USB from macOS Install Image
Click 'Load DMG' to import your DMG file into the program. Insert a blank DVD and click Burn against the DVD option to write the DMG to the disk.
In three simple steps, your bootable DVD is ready. You won't find that many tools that are so easy to operate. DMGGeeker also has one of the highest burn success rates in its class, which means no wasted DVDs and no wasted time.
Summary
What Is Disk-o.dmg Called
How to choose the rignt tool depends on what the purpose is. If you want to use a DMG file in Windows to mount a version of Mac OS X, then Method 1 will work. However, most of the time, you'll need a DMG to install an OS version on a Mac computer. In those cases, if all you have to work with is a Windows PC, DMGGeeker is the perfect application. It's simple enough for a novice yet robust enough for a professional, it contains all the tools you need to manage DMG files, and it's a life-saver if you only have a Windows PC to work with.