To create a bootable USB drive from a DMG file on Windows, you will need to have the right utility. That's because DMG is not native on Windows. It is the Mac equivalent of an ISO file that has been in use since Apple transitioned from the IMG format with Mac OS X. A DMG file, like ISO, can be used to install macOS operating system or Mac apps. If the Mac computer was broken or crashed and couln't get into the system, but you only have access to a Windows PC, there's still a way to make a bootable macOS install USB on Windows.
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. New Disk Image Format (NDIF) was the previous default disk image format in Mac OS 9, and disk images with this format generally have a.img.
This article looks at three applications that you can use to create a bootable USB drive from a DMG file in Windows. All of them have their advantages and disadvantages, which we have highlighted. You can make the best choice for you based on the information provided below. They are in no particular order of preference.
TransMac - Make DMG File Bootable USB on Windows
This is a fairly robust application for creating bootable USB on Windows from a DMG file. However, there's a preparatory step to be executed before you can create the bootable USB drive. The typical disk partition used is MBR, but you will need to do a partition with GPT for this to work. You can do so by executing the diskpart command in Windows CMD. Alternatively, you can do it from within TransMac, as shown in the instructions shown below the next paragraph.
![Dmg Img Dmg Img](/uploads/1/2/4/2/124289982/231718738.jpg)
Once this is done, you can download TransMac and use the two-week free trial period to get the job done free of cost. You can always upgrade if you like the utility and want to keep using it after the trial period has ended. Once you download and install the application, insert your formatted USB drive and follow the instructions below:
Step 1: If you haven't formatted the USB, right-click on your USB drive in the left panel and select Format Disk for Mac from the contextual menu.
Step 2: Right-click again on the drive in the left panel and this time select Restore with Disk Image.
Step 3 : Select the DMG file and click on Open. Once the process is complete, you can eject the drive and use it on a Mac. To boot from this media, hold down the Option key and fire up your Mac.
Convert DMG to ISO and Create macOS Boot USB from Windows
Since ISO is a better format for Windows, you can also convert the DMG to the ISO format and then use the ISO disk image to create the bootable USB. Please note that you can't boot your Mac from bootable USB made from an ISO file, which means you'll have to convert it back to DMG prior to that. Still, it's an effective way to create bootable media for a Mac computer. Here's how it works:
Step 1: Once you have the macOS install DMG file on a Windows PC, click on Windows + R to open the run dialog box, and type in CMD, then hit Enter. When the Command Prompt opens up, use the following command to convert the file to ISO:
hdiutil convert /path/sourceimagefile.dmg -format UDTO -o /path/targetmage.iso
hdiutil convert /path/sourceimagefile.dmg -format UDTO -o /path/targetmage.iso
Step 2: Download and install UUByte ISO Editor on your PC, insert the USB drive and launch the application.
Step 3: Click Burn button on the main screen and point to the converted ISO file. The drive will be automatically detected and click on Burn icon to burn the ISO to the USB drive.
Once the ISO is burned to the file, you can insert it into a Mac and convert it back into the DMG format. Since you're converting the file twice, there's a chance that the file could get corrupted in the process. If that happens repeatedly, then try this next method.
PowerISO: Make Bootable Mac Install USB on Windows 10/8/7
This Windows utility allows you do create bootable USB from DMG on a PC. You can also edit the DMG or extract the contents, and there's also an option to copy it to a disk. For this particular exercise, we'll show you how to use PowerISO to create a bootable USB drive on Windows without having to convert the disk image into another format like ISO.
Step 1: Download and install the application on your PC.
Step 2: Insert your USB drive and launch PowerISO.
Step 3: In the Tools menu, select 'Create Bootable USB Drive… '. You will need to give admin privileges to the software. Alternatively, you can run the program as admin when you launch it.
Step 4: Select the USB drive in the section called Destination USB Drive.
Step 5: Leave all other default as they are and click on 'Start' to burn DMG to the USB drive.
You should be able to see the progress, and a new popup will appear when the bootable media is ready. You can now eject the media and use it to run the DMG on a Mac computer.
Conclusion:
All of these methods are workable, so select the right one for you based on your level of knowledge and your preference.
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 |
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.
- 3File format
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]
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.
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
Retrieved from 'https://en.wikipedia.org/w/index.php?title=Apple_Disk_Image&oldid=917998972'