So youâre running Linux on your computer, maybe Ubuntu, and you have some files with the .dmg extension. In this guide, weâre going to talk about how to open, mount, extract, and otherwise get your files from these pesky DMG images. You could always just extract the files on a Mac, then transfer them back to your Linux machine. But if you really want to do this on Linux, without having to rely on Mac, hereâs how to do it.
DMG EXtractor will open and extract Mac OS X dmg files on PC. Watch how it's done (1:04) Our users are saying 'I extracted a very important.dmg file! DMG Extractor.
What are DMG image files?
Simply put, itâs a kind of image file. But not an image like a jpeg is an image. DMG is Appleâs proprietary disk image format, native to Mac OS X. There are actually a whole bunch of different types, format and options within this format. There are options for encryption, compression, and different kinds of partition schemes, among others. Unfortunately, this can make things pretty confusing when weâre trying to gain access to the data contained in one of these images.
DMG images are typically a kind of Universal Disk Image Format (UDIF), although there are others, namely NDIF and SPARSE. Although the .dmg file extension is usually used, they can also sometimes have an .img extension, or in some cases no extension at all. Their MIME type is application/x-apple-diskimage.
The HFS/HFS+ (Mac OS Extended/Journaled) file system is typically used in DMGs. However, this isnât always the case. You may also sometimes find FAT and ExFAT files systems, as well as variations on HFS.
Does my system support DMG?
Perhaps the biggest hurdle to overcome when trying to work with DMG files is working with the HFS file system (Mac OS Extended). Linux supports HFS through the âhfsâ and âhfsplusâ kernel modules.
Thereâs an easy way to test if your system has these kernel modules. Plug in a USB drive formatted with the Mac OS Extended file system. If your particular distribution doesnât have the appropriate modules, you will likely get an error message. On Ubuntu, youâll get a popup window declaring âUbuntu: Unable to mount '.
Alternatively, we can see if the kernel module files are present with find:
We want to see two files: âhfs.koâ and âhfsplus.koâ. If find doesnât return these files, your system probably doesnât support HFS.
You could also try âmodinfoâ:
modinfo hfs and modinfo hfsplus should return something like:
If you get '
modinfo: ERROR: Module hfsplus not found ' your system doesnât have these modules.
Not all Linux kernels and distributions support HFS. This is especially the case for certain distributions that are a few years old. If you have kernel support for HFS, great! If not, donât worry. There are still ways to extract data from your DMG files. While itâs nice to have the option to mount the images weâre working with, this is really the only functionality weâre losing without having the hfs and hfsplus modules. The two programs weâre going to use later on (P7ZIP and dmg2img) do not require kernel support to function.
What kinds of DMG images can be opened in Linux?
This guide is about how to open, mount, and extract files from read/write, read only, and compressed DMG image files. The following partition schemes have all been tested with the techniques discussed here.
This guide does not cover how to handle sparse disk images (.sparseimage), sparse bundle disk images (.sparsebundle), or CD/DVD masters. DMG images with partition scheme types of âCD/DVDâ and âGUID Partition Mapâ do not appear to work with the techniques described here.
Option 1: Mount the DMG
If the Linux distribution youâre on has HFS support in the kernel (Ubuntu 14.04.1 LTS supports it), itâs pretty easy to just mount the DMG image:
Weâre using âsudoâ because we need root privileges to mount things. The HFS+ file system type is specified with â-t hfsplusâ. The â/mntâ at the end of the command specifies where weâre mounting the image.
Unmount the image with
sudo umount /mnt
If you get a wrong fs type message like the one below, it means the DMG file is either of an unsupported type, or itâs compressed. Unsupported images include sparse images, sparse disk bundles, CD/DVD masters, and images with partition schemes of the CD/DVD or GUID Partition Map types.
Use âfileâ to learn a little more about the image file:
If you get
image.dmg: x86boot sector that means itâs probably using a GUID Partition Map and isnât supported. This isnât good, however, itâs also not too terribly common.
Whatâs more common is to see something like this:
If mounting isnât working, and this is what youâre seeing with âfile image.dmgâ, then youâre luck!. Our problems are being caused by compression. Linux doesnât like to mount compressed DMG images. To get around this little obstacle, weâll use dmg2img (see below).
Option 2: Use dmg2img for compressed images
So you have a DMG image that you canât mount because itâs compressed. Youâve done âfile compressed_image.dmgâ and you got âcompressed_image.dmg: bzip2 compressed dataâ. The fix? Thatâs easy: use dmg2img to convert it to an uncompressed image. Once you run the image through dmg2img you should be able to mount it no problem.
Donât have dmg2img? Itâs usually pretty easy to get using your distributionâs package management. On Ubuntu, youâd do:
Using dmg2img isnât very difficult. Type âdmg2imgâ into the command line followed by the name of the DMG file you want to decompress. The Mac OS X version of Firefox is a good example of a compressed DMG file.
Now mount the resulting .img file:
Option 3: Extract DMG contents with P7ZIP
P7ZIP is awesome. Itâs the Linux/BSD version of 7-Zip. Check out their SourceForge page here With it you can literally extract files from any kind of image or archive. Just kidding⦠It doesnât really work with every format conceivable. However, it can handle (in alphabetical order): ARJ, CAB, CHM, CPIO, CramFS, DEB, DMG, FAT, HFS, ISO, LZH, LZMA, MBR, MSI, NSIS, NTFS, RAR, RPM, SquashFS, UDF, VHD, WIM, XAR and Z. Impressed? I certainly am!
Installing p7zip is pretty easy using your distributionâs package management system. On Ubuntu with apt-get:
In addition to being able to extract data from compressed and uncompressed images alike, P7ZIP doesnât require the HFS kernel modules at all. In the example below, weâre going to extract all of the files from âFirefox 33.1.1.dmgâ. When weâre done, weâll have a tidy little folder called âFirefoxâ.
Invoke P7ZIP to extract archives and images with â7z xâ.
Notice that 7z extracted three files: â0.ddmâ, â1.Apple_partition_mapâ, and â2.hfsâ. To actually get to the files, weâll need to run 7z again on â2.hfsâ.
We picked â2.hfsâ because it was the biggest of the three, meaning it was probably the one with the data. Simple but effective logic. After a few moments, you should have a folder called âFirefoxâ with all of the files from the original DMG.
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.
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.
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.
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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 WindowsHow To Open Dmg On Mac Download
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
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.
How To Open .dmg.part Files On Mac
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.
How To Open Dmg On Mac Computer
Step 1: Download and install the application on your PC.
How To Unzip Dmg Files On Mac
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.
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