When you open DMG file this way, disk image stored inside DMG file will be mounted, and then opened in a separate Finder window. If DMG contains installation of an application, then installation window of the app will open. If not, then you will see the disk image content. Hi I just bought Mountain Lion from the Mac App Store. I need to make a backup USB. But when I try to open InstallESD.dmg, it says 'The following disc images couldnt be opened Install ESD.dmg Not recognized. Could anyone help me? Any help would be appreciated!

1. Macos See Which Dmg Was Last Opened Today
2. Macos See Which Dmg Was Las Opened Now
3. Macos See Which Dmg Was Las Opened Today

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.

When you see a -7% or something or that nature usually its a penalty because the gun might have an unusally high bonus to something else like acc or reloading or clip size. If it doesnt and just has a -7% dmg mod on it scrap it. Borderlands guns with negative dmg. Oct 30, 2009  The gun damage is the final numbers u need to worry about if ur SMG is let say 67x4 it means it gona shoot 4 bullet of 67 damage eatch time u squeeze the trigger Please sign your posts, so we know who we're talking to! (negative) Weapon Damage weapons are a thing? Going through the campaign again with Flak and just got a Jakobs pistol with -62% weapon damage. Is this how they did the hotfix nerf for Jakobs pistols? Sep 13, 2019  You want to pay attention to the damage type on the gun you’re using in Borderlands 3.You’re going need to understand what kind of weapon you’re using when you’re fighting off foes to take. Gun dmg is the guns base damage so whatever the card says it is. Crit damage works a bit different, every gun except snipers, assault rifles and launchers have a 2x dmg. Snipers have a hidden bonus on top of the 2x, forget what it is.

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]

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:

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]

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. ^'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'. DataForensics.org. 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

Running the latest software is not always the best decision. There are plenty of reasons you might want to downgrade or run an older version of macOS on your computer.

You may find that after the latest update your computer runs slower, your apps don’t function, or that the programs you need to run are not yet compatible with the upgrade. Maybe as a developer, you want to create a test environment to ensure your software runs properly in all available versions of OS X - check out the infographic below. Or you may simply like the look of the old version better (no judgement) and not want to upgrade until absolutely necessary.

Keep your apps while downgrading

Get Setapp, a collection of Mac apps that strengthen your macOS. Whenever you decide to downgrade, your apps will travel with you.

How to Install Old OS X on Your Mac

Although you might think that going back to the old macOS is not possible by looking at the App Store Updates tab, it’s actually quite easy to do. In this article, we’ll take you through everything you need to download and install an old OS X on your Mac.

Prepare your Mac first

Make sure you are ready to downgrade your operating system by checking in with what version of OS X you already have and ensuring you have enough hard drive room to download the older version. Clicking the apple in the top left corner of your desktop and selecting About This Mac will allow you to see what OS X version you are currently running. Tabbing over to Storage will let you know how much disk space you have available. You’ll need around around eight gigabytes free depending on which macOS you downgrade to.

Jan 02, 2009  After installing a program or application on Mac, do you need to keep the original dmg file, or can you just delete it? On a game it usually functions as cd, so I keep those files. But after installing a program like Google Earth and putting the needed file in Applications, do I need to keep the original dmg file used to install it to make it work, or can I just delete it? Dec 27, 2006  I'm new to the world of Macs, and I was just wondering after I download something from the Internet, do I need to keep the.dmg file that is on my desktop? Specifically, I downloaded Senuti, so do I need to keep that.dmg file on my desktop in order for the application to work? Thank you for any advice you can offer. That is essentially all you need to know when it comes to extracting the contents of DMG files to your Windows PC. If you do not want to download these programs, one other option is to follow our guide on how to convert DMG files to ISO’s. After that conversion is done, you can mount the ISO in Windows and access the files that way. After you download a program do you need dmg.

Even if you do have enough space, it’s a good idea to clean your computer before installing the desired operating system. You can, of course, do so manually by deleting unused files and uninstalling old software to free up disk space. Depending on how tidy you are, this might take quite a bit of time.

To make things easy, use a specialized app like CleanMyMac, which will quickly free up space by detecting unused apps and large files, and offering to completely delete them, with all their hidden corresponding files, in one quick click.

Optimizing your Mac with CleanMyMac is effortless:

1. Launch CleanMyMac
2. Select the Smart Scan tab and click Scan
3. Review Details to see the list of suggested optimizations
4. Click Clean

To uninstall certain apps, find the Uninstaller tab and select the apps you haven’t been using for a while.

Download CMM X to prepare for Catalina

The only solution that will free up disk space, uninstall 32-bit apps, and solve tons of problems to prepare your Mac for a new macOS.

The final preparation step is to make sure you back up all your important files to cloud storage or an external drive. A proper backup app like Get Backup Pro can save you a lot of headache here.

Macos See Which Dmg Was Last Opened Today

To create a new backup with Get Backup Pro:

1. Connect your external hard drive
2. Click the plus icon in the bottom left corner
3. Type in the name for your backup
4. Choose your external drive as a destination
5. Adjust all the settings according to your preference and click OK
6. Tap the play button once you ready to perform the backup

Grab an old macOS with Setapp

Downgrading to previous operating systems on Mac gets easier. To put it shortly, Setapp has your back here.

Download the OS X you want

Once you have space on your computer, figure out what version of OS X you would like to install. You can see all previous versions of OS X your Mac has installed by opening up the App Store and clicking the icon in Applications. Tab to the Purchase page of the menu and scroll down to find the line for previous operating systems. Clicking the install button of the macOS you want will begin downloading the file.

What if I can’t find the version I want in the app store?

If your goal is to download a version of macOS that you have not already used, or, that was not available as an update from the App Store after you bought your Mac, you may need to purchase it. The earliest versions, OS X Lion and OS X Mountain Lion are available on the Apple Store’s website and arrive to you via email for download. OS X Snow Leopard ships as a boxed version and requires a disk drive to install.

It could be helpful to know where you sit on the timeline of macOS X updates. Below is a chronological list of all the updates beginning with the most recent update, High Sierra, released in 2017:

• OS X High Sierra 10.13
• OS X Sierra 10.12
• OS X ElCapitan 10.11
• OS X Yosemite 10.10
• OS X Mavericks 10.9
• OS X Mountain Lion 10.8
• OS X Lion 10.7, released in 2011

Visiting the Apple Support’s Downloads page makes it easy to search for any version of macOS you might need, and most are available for free. Downloads for previous versions of OS X are linked below and include:

Alternative sources for downloading macOS

If you can’t find the version you want from Apple, ask a friend who is running the macOS you’re looking for to make a copy of the installer file for you. Downloading a .dmg file from a torrent site may seem a quick solution, but it means risking your security. Alternatively, you could hit up your nearest Apple Store. They will likely have image files of all the different versions of the software and help you install it right there as well.

Install the macOS

If you download the file from the App Store, the installer will start immediately. Follow the prompts and be prepared to restart your computer. If you acquire the installer from another source, just downloading the file will not install the OS X right away on your Mac, you’ll need to find the file in your Downloads or Applications folder, then open and run the installer from the downloaded file.

I can’t download an old version of Mac OS X

A downgrade is different than an upgrade. When you try to downgrade macOS, the installer may not launch right away depending on which versions of macOS you are moving between. If your installer does not launch, or you get an error message that reads: “This copy of the ‘Install OS X’ application is too old to be opened on this version of OS X,” you’ll need to use a bootable USB or external drive to work around this problem.

Get a bootable drive with OS X

Creating a bootable USB or a bootable drive is not complicated. You’ll need an external drive with enough space to hold your desired OS X on it and a basic familiarity with Terminal, Apple’s command line interface.

If you’re uncomfortable using Terminal to execute basic commands, use an app like Disk Drill to help create a boot drive. Whether you use Terminal or Disk Drill, our guide on creating a bootable installer will walk you through all the necessary steps.

Remove the old OS X

Once your drive is prepared with your bootable version of OS X, erase the unwanted version. After you restart your computer, press and hold Command + R. When you enter the macOS Utilities screen, navigate to Disk Utility, click continue, and find your Startup Disk. Tab to the Erase page and name the file you want erased (e.g. macOS High Sierra). Then select Mac OS Extended (Journaled) from the dropdown menu. Hit Erase and quit out of Disk Utility. This will return you to the OS X Utilities selector.

Install the bootable version of OS X

Macos See Which Dmg Was Las Opened Now

If you used Disk Drill for creating your bootable drive, a window will prompt your actions for using the install disk you made. But if you created your own using Terminal, use OS X Utilities Selector and find Reinstall OS X. Find and select your install disk with your bootable version of your preferred macOS, and click continue through to the license agreement. Once you agree, you should be prompted by the installer. Once the installation is completed, your computer should restart. If it does not restart itself, make sure you restart it normally. The downgrade should be complete!

As you can see, downgrading your OS X is not as dreadful as you might think, especially if you use helper apps like CleanMyMac, Get Backup Pro, and Disk Drill — all of which are available for a free trial on Setapp. So downgrade away!

macOS evolution inforgaphic

Macos See Which Dmg Was Las Opened Today