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Dec 30, 2018 mv /tmp/Mojave.cdr.dmg /Desktop/InstallSystem.dmg hdiutil detach /Volumes/Install macOS Mojave formattedPrint ' Converting the disk image to an ISO file and cleaning up. Jun 17, 2019 mv /tmp/HighSierra.cdr.dmg /Desktop/InstallSystem.dmg hdiutil detach /Volumes/Install macOS High Sierra hdiutil convert /Desktop/InstallSystem.dmg -format UDTO -o /Desktop/HighSierra.iso and then you can rename HighSierra.iso.cdr to HighSierra.iso. You can then use this to burn it to a dual layer dvd.
An ISO file contains optical disc file system and contains elements that would be written in optical disc. It comes with .iso extension but sometime .img extension is also used in some cases like Microsoft Dreamspark. The file which doesn’t contain ISO 9660 but have UDF which comes with .udf extension. It is sector by sector copy of data.
What is ISO FILE
The DMG image format is by far the most popular file container format used to distribute software on Mac OS X. Here’s how to convert a DMG file into an ISO file that can be mounted on a Windows PC.
The full form of ISO is International Organisation for Standardization. The ISO name is taken from ISO 9660, used with CD ROM media but it contain a UDF(ISO/IEC 13346) file system ( used for DVDs and Blu-ray Discs). Most of the operating systems like Unix, Linux and Mac OS have built in capability to mount an ISO. Most of the emulator uses .ISO file to create image of CD. Emulator like PCSX2, Dolphin use .iso to emulate Wii and GameCube games and Playstation 2 games respectively.
Benefits of ISO file
- It is the program file which is neatly copied in a single file and it is used to distribute large program over the internet.
- It is used to create backup of CD or DVD because it creates the exact copy carry, and converts all the data with bits from the disc. Whenever the file is copied, it lacks the header file but when iso file is created it covers all the things including the header file.
Softwares used to create iso file
- ISO Recorder
- Magic ISO
- Power ISO
- Any to ISO
Dmg To Iso Mac
What is .dmg file
DMG file is Apple disc image which is used for Mac OS. It comes with .dmg extension. DMG stands for Disc Image File. It has UDIF(Universal Disc Image Format) for Mac OS X with .dmg extension. It is capable for the compressed, encrypted data, file spanning amd some of which are password protected. It is downloaded from internet and mounts a virtual disc on the desktop when opened. Disc image file is only used for Mac OS not for the Windows. DMG file support 128-bit and 256-bit AES encryption.
Benefits of .dmg file:
- It has supporting feature for creating hybrid optical media, that has multiple file system
- It also supports some of the file system like Hierarchical File System (HFS) , HFS Plus, ISO 9660, Universal Disc Format (UDF), File Allocation Table(FAT).
- DMG files are read only file ,allow the file to change nothing after being created. This makes the software more secure and free from any virus.
- It is easy to send more than one file over the internet that contains software and its Installer.
- It has ability to show multilingual software licence agreement before mounting the disc image.
We have so much in Mac that would make it easy for us to convert an ISO file to DMG and DMG file to ISO and also no additional software is required. Although there are some processes that would be used to convert the DMG file into ISO file in Mac OS X.
The first process is by using opening disc utility , the second process comes with the command line and the third via different software.
Opening Disc Utility
This is a powerful technique. We should be careful while doing this because by our single mistake it would easily wipe out data from some of our discs. So be cautious.
Explanation of process:
- First of all we have to insert the CD/ DVD which contains the file that we want to convert into a CD burning capable mac.
- After that, go to the Finder file and open it. After opening click on the application and then double click on the Utilities folder.
- After that, to open the Disc Utility, double click on the application.
Creating DMG file
- After opening the Disc Utility window, go to left and check name of the disc that we want to insert in the highlighted region.
- Then click on the file menu which is at the top and go to downward menu option, click New, then click on Disc Image (name of our disc).
- Give a name to new file and navigate on the desktop to save the file there.
- Choose the compressed image format
- Click on save menu and now we have .dmg file save in the desktop. Now our next task is to burn the file onto a blank CD/DVD.
Burning the DMG file
- Take out the original CD/DVD from the computer and put a blank CD/DVD on it. If you promoted with a pop-up window, click ignore.
- Then after return to Disc Utility and go to top of the window and click the Burn button.
- Then after, go and check out on the desktop and highlight the .dmg file and save. Then click on Burn button.
- Click Burn again in the new window to set the new default setting.
- CD/DVD is automatically ejected, once the program is finished. Now we have a burned CD or DVD with a copy of original file saved in .dmg format.
Second Method
Using Command line:
This is the easiest method to convert the ISO file into DMG by using command line.
Explanation:
- Go to the Finder and open it, then open the terminal by clicking GO > Terminal
- Type the following command on the terminal
- hdiutil convert /path/imagefile.iso –
- format UDRW -o /path/convertedimage.dmg , here /path/imagefile.iso is the path to the file.
- Then after press Enter , it will take few seconds or minutes according to the size of file. After completion, the file comes with .CDR extension. Just rename it to .ISO . The file is ready to use.
Third method via different software
Softwares which are capable to convert the ISO file into DMG
Some of the softwares atr also used to convert the ISO file to DMG file. Some of them are
- MagicISO: It is a software which is capable to convert many format into disc image file. Click on the MagicISO then click on the File and then click on open our ISO file. Click on Property and then Apple Disc Image and click Save. The ISO file is converted to DMG file. To download the MagicISO go to the official website www.magiciso.com . It is available for 64 bit as well as for 32 bit.
- PowerISO: It is also another software which is capable of converting many types of format into disc image file. Open the Power ISO and click File and then click on open ISO file. Click on the Properties and then select the Apple Disc Image. Click on the File icon and save it from the drop down menu and click Save. The ISO file is converted to DMG and ready to use. To download the PowerISO go to official website www.poweriso.com .
- Nero Burning Rom: Like the MagicISO and PowerISO, Nero Burning Rom is also used to convert the ISO file into DMG file. Click on the Nero Burning Rom amd click on the File and then click on open the ISO file and then click on the File and Save As dialog box. “Output File Type” property is changed Disc Image File and the Save it . This is how we convert the ISO file to DMG using Nero Burning Rom. DMG file is ready to use. To download the Nero Burning Rom go to the Official website www.nero.com .
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Manipulate disk images (attach, verify, burn, etc).
Disk images are containers that emulate disks. Like disks, they can be partitioned and formatted. Many uses of disk images blur the distinction between the disk image container and its content, but this distinction is critical to understanding disk images. The terms 'attach' and 'detach' are used to distinguish the way disk images are connected to and disconnected from the system.
For example, when you double-click a disk image in the macOS Finder, two separate things happen. First, the image is 'attached' to the system just like an external drive. Then, the kernel and Disk Arbitration probe the new device for recognized file structures. If any file structures are understood, the associated volumes will mount and appear in the
Finder.
Always consider whether a 'disk image' operation applies to the blocks of the disk image device or to the (often file-oriented) content of the image. For example, verify verifies that the blocks stored in a read- only disk image have not changed since it was created. On the other hand, create -srcfolder creates a disk image container, puts a filesystem
in it, and then copies the specified files to the new filesystem.
For example, when you double-click a disk image in the macOS Finder, two separate things happen. First, the image is 'attached' to the system just like an external drive. Then, the kernel and Disk Arbitration probe the new device for recognized file structures. If any file structures are understood, the associated volumes will mount and appear in the
Finder.
Always consider whether a 'disk image' operation applies to the blocks of the disk image device or to the (often file-oriented) content of the image. For example, verify verifies that the blocks stored in a read- only disk image have not changed since it was created. On the other hand, create -srcfolder creates a disk image container, puts a filesystem
in it, and then copies the specified files to the new filesystem.
As of macOS 10.5, a more reliable, efficient, and scalable sparse format, UDSB (SPARSEBUNDLE), is recommended for persistent sparse images as long as a backing bundle (directory) is acceptable. macOS 10.5 also introduced
F_FULLFSYNC over AFP (on client and server), allowing proper journal flushes for HFS+J-bearing images. Critical data should never be stored in sparse disk images on file servers that don't support F_FULLFSYNC.
SPARSE (UDSP) images and shadow files were designed for intermediate use when creating other images (e.g. UDZO) when final image sizes are unknown. As of macOS 10.3.2, partially-updated SPARSE images are properly handled and are thus safe for persistent storage. SPARSE images are not recommended for persistent storage on versions of macOS earlier than 10.3.2 and should be avoided in favor of SPARSEBUNDLE images or UDRW
images and resize.
If more space is needed than is referenced by the hosted filesystem, hdiutil resize or diskutil(8) resize can help to grow or shrink the filesystem in an image. compact reclaims unused space in sparse images. Though they request that hosted HFS+ filesystems use a special 'front first' allocation policy, beware that sparse images can enhance the
effects of any fragmentation in the hosted filesystem.
To prevent errors when a filesystem inside of a sparse image has more free space than the volume holding the sparse image, HFS volumes inside sparse images will report an amount of free space slightly less than the amount of free space on the volume on which image resides. The image filesystem currently only behaves this way as a result of a direct attach action and will not behave this way if, for example, the filesystem is unmounted and remounted.
F_FULLFSYNC over AFP (on client and server), allowing proper journal flushes for HFS+J-bearing images. Critical data should never be stored in sparse disk images on file servers that don't support F_FULLFSYNC.
SPARSE (UDSP) images and shadow files were designed for intermediate use when creating other images (e.g. UDZO) when final image sizes are unknown. As of macOS 10.3.2, partially-updated SPARSE images are properly handled and are thus safe for persistent storage. SPARSE images are not recommended for persistent storage on versions of macOS earlier than 10.3.2 and should be avoided in favor of SPARSEBUNDLE images or UDRW
images and resize.
If more space is needed than is referenced by the hosted filesystem, hdiutil resize or diskutil(8) resize can help to grow or shrink the filesystem in an image. compact reclaims unused space in sparse images. Though they request that hosted HFS+ filesystems use a special 'front first' allocation policy, beware that sparse images can enhance the
effects of any fragmentation in the hosted filesystem.
To prevent errors when a filesystem inside of a sparse image has more free space than the volume holding the sparse image, HFS volumes inside sparse images will report an amount of free space slightly less than the amount of free space on the volume on which image resides. The image filesystem currently only behaves this way as a result of a direct attach action and will not behave this way if, for example, the filesystem is unmounted and remounted.
/dev Entry Access
Since any /dev entry can be treated as a raw disk image, it is worth noting which devices can be accessed when and how. /dev/rdisk nodes are character-special devices, but are 'raw' in the BSD sense and force block-aligned I/O. They are closer to the physical disk than the buffer cache. /dev/disk nodes, on the other hand, are buffered block-special
devices and are used primarily by the kernel's filesystem code.
It is not possible to read from a /dev/disk node while a filesystem is mounted from it, but anyone with read access to the appropriate /dev/rdisk node can use hdiutil verbs such as fsid or pmap with it. The DiskImages framework will attempt to use authopen(1) to open any device which it can't open (due to EACCES) for reading with open(2). This might cause apparent hangs while trying to access /dev entries while logged in remotely (an authorization panel is waiting on console).
Generally, the /dev/disk node is preferred for imaging devices (e.g. convert or create -srcdevice operations), while /dev/rdisk is usable for the quick pmap or fsid. In particular, converting the blocks of a mounted journaled filesystem to a read-only image will prevent the volume in the image from mounting (the journal will be permanently dirty).
devices and are used primarily by the kernel's filesystem code.
It is not possible to read from a /dev/disk node while a filesystem is mounted from it, but anyone with read access to the appropriate /dev/rdisk node can use hdiutil verbs such as fsid or pmap with it. The DiskImages framework will attempt to use authopen(1) to open any device which it can't open (due to EACCES) for reading with open(2). This might cause apparent hangs while trying to access /dev entries while logged in remotely (an authorization panel is waiting on console).
Generally, the /dev/disk node is preferred for imaging devices (e.g. convert or create -srcdevice operations), while /dev/rdisk is usable for the quick pmap or fsid. In particular, converting the blocks of a mounted journaled filesystem to a read-only image will prevent the volume in the image from mounting (the journal will be permanently dirty).
Compatibility
macOS 10.0 supported the disk images of Disk Copy 6 on Mac OS 9. macOS 10.1 added sparse, encrypted, and zlib-compressed images. These images will not be recognized on macOS 10.0 (or will attach read/write, possibly allowing for their destruction). As the sparse, shadow, and encrypted formats have evolved, switches have been added to facilitate the creation of images that are compatible with older OS versions (at the expense of the performance and reliability improvements offered by the format enhancements). In particular, sparse images should not be expected to attach on versions of macOS older than that which created them.
With macOS 10.2, the most common image formats went 'in-kernel' (i.e. the DiskImages kernel extension served them without a helper process), image meta-data began being stored both as XML and in the embedded resource fork, and the default Disk Copy.app 'compressed' format became UDZO (breaking compatibility with 10.0). macOS 10.4 introduced bzip2 compression in the UDBZ format which provides smaller images (especially when combined with makehybrid) at the expense of backwards compatibility.
In macOS 10.4.7, the resource forks previously embedded in UDIF images were abandoned entirely to avoid metadata length limitations imposed by resource fork structures. As a result, UDIF images created on 10.4.7 and later will not, by default, be recognized by either macOS 10.1 or macOS 10.0. flatten can be used to customize the type of metadata stored in the image.
macOS 10.5 introduced sparse bundle images which compact quickly but are not recognized by previous OS versions. macOS 10.6 removed support for attaching SPARSEBUNDLE images from network file servers that don't support F_FULLFSYNC.
macOS 10.7 removed double-click support for images using legacy metadata; these can be rehabilitated using flatten and unflatten, or convert.
With macOS 10.2, the most common image formats went 'in-kernel' (i.e. the DiskImages kernel extension served them without a helper process), image meta-data began being stored both as XML and in the embedded resource fork, and the default Disk Copy.app 'compressed' format became UDZO (breaking compatibility with 10.0). macOS 10.4 introduced bzip2 compression in the UDBZ format which provides smaller images (especially when combined with makehybrid) at the expense of backwards compatibility.
In macOS 10.4.7, the resource forks previously embedded in UDIF images were abandoned entirely to avoid metadata length limitations imposed by resource fork structures. As a result, UDIF images created on 10.4.7 and later will not, by default, be recognized by either macOS 10.1 or macOS 10.0. flatten can be used to customize the type of metadata stored in the image.
macOS 10.5 introduced sparse bundle images which compact quickly but are not recognized by previous OS versions. macOS 10.6 removed support for attaching SPARSEBUNDLE images from network file servers that don't support F_FULLFSYNC.
macOS 10.7 removed double-click support for images using legacy metadata; these can be rehabilitated using flatten and unflatten, or convert.
History
Disk images were first invented to electronically store and transmit representations of floppy disks for manufacturing replication. These images of floppies are typically referred to as 'Disk Copy 4.2' images, in reference to the application that created and restored them to floppy disks. Disk Copy 4.2 images were block-for-block representations of a floppy
disk, with no notion of compression. DART is a variant of the Disk Copy 4.2 format that supported compression.
NDIF (New Disk Image Format) images were developed to replace the Disk Copy 4.2 and DART image formats and to support images larger than a floppy disk. With NDIF and Disk Copy version 6, images could be'attached' as mass storage devices under Mac OS 9. Apple Data Compression (ADC) -- which carefully optimizes for fast decompression -- was
used to compress images that were typically created once and restored many times during manufacturing.
UDIF (Universal Disk Image Format) device images picked up where NDIF left off, allowing images to represent entire block devices and all the data therein: DDM, partition map, disk-based drivers, etc. For example, it can represent bootable CDs which can then be replicated from an image.
To ensure single-fork files (NDIF was dual-fork), it began embedding its resource fork in the data fork. UDIF is the native image format for OS X.
Raw disk images from other operating systems (e.g. .iso files) will be recognized as disk images and can be attached and mounted if macOS recognizes the filesystems. They can also be burned with hdiutil burn.
disk, with no notion of compression. DART is a variant of the Disk Copy 4.2 format that supported compression.
NDIF (New Disk Image Format) images were developed to replace the Disk Copy 4.2 and DART image formats and to support images larger than a floppy disk. With NDIF and Disk Copy version 6, images could be'attached' as mass storage devices under Mac OS 9. Apple Data Compression (ADC) -- which carefully optimizes for fast decompression -- was
used to compress images that were typically created once and restored many times during manufacturing.
UDIF (Universal Disk Image Format) device images picked up where NDIF left off, allowing images to represent entire block devices and all the data therein: DDM, partition map, disk-based drivers, etc. For example, it can represent bootable CDs which can then be replicated from an image.
To ensure single-fork files (NDIF was dual-fork), it began embedding its resource fork in the data fork. UDIF is the native image format for OS X.
Raw disk images from other operating systems (e.g. .iso files) will be recognized as disk images and can be attached and mounted if macOS recognizes the filesystems. They can also be burned with hdiutil burn.
What's New
In macOS 10.12 Apple will provide an updated hdutil command able to work with the new file system.
macOS 10.7 added the ability to quickly render encrypted images inaccessible using the new erasekeys verb, which saves time versus securely overwriting the entire image.
In macOS 10.6, pmap was rewritten to use MediaKit's latest reporting routines so that it can properly support GPT partition maps. Also -debug now implies -verbose for all verbs.
macOS 10.5 changed the behavior of attach when run on an existing image or /dev node: if the image was attached but no volume was mounted, the volume would be mounted. Prior systems would return the /dev without mounting the volume. This change effectively removes the ability to create a second /dev node from an existing one.
In macOS 10.6, pmap was rewritten to use MediaKit's latest reporting routines so that it can properly support GPT partition maps. Also -debug now implies -verbose for all verbs.
macOS 10.5 changed the behavior of attach when run on an existing image or /dev node: if the image was attached but no volume was mounted, the volume would be mounted. Prior systems would return the /dev without mounting the volume. This change effectively removes the ability to create a second /dev node from an existing one.
Examples
Mount a Disk Image:
$ hdiutil attach /path/to/diskimage.dmg
$ hdiutil attach /path/to/diskimage.dmg
Unmount a Disk Image:
$ hdiutil detach /dev/disk2s1
$ hdiutil detach /dev/disk2s1
Create a Disk Image from a folders contents:
$ hdiutil create -volname 'Volume Name' -srcfolder /path/to/folder -ov diskimage.dmg
$ hdiutil create -volname 'Volume Name' -srcfolder /path/to/folder -ov diskimage.dmg
Create an encrypted Disk Image from a folders contents:
$ hdiutil create -encryption -stdinpass -volname 'Volume Name' -srcfolder /path/to/folder -ov encrypted.dmg
$ hdiutil create -encryption -stdinpass -volname 'Volume Name' -srcfolder /path/to/folder -ov encrypted.dmg
The required password can be piped into the hdiutil command:
echo -n SEcurePa$$w0rd | hdiutil...
echo -n SEcurePa$$w0rd | hdiutil...
Burn a Disk Image file (.iso, .img or .dmg) to a DVD:
$ hdiutil burn /path/to/image_file
$ hdiutil burn /path/to/image_file
“The beginning of wisdom is to call things by their right names” - Chinese Proverb
Related macOS commands:
asr - Apple Software Restore.
dd - Convert and copy a file, clone disks.
diskutil - Disk utilities - Format, Verify, Repair.
ditto - Copy files and folders.
authopen(1), hdid(8), ioreg(8), drutil(1), msdos.util(8), hfs.util(8), diskarbitrationd(8), /System/Library/CoreServices/DiskImageMounter.app.
dd - Convert and copy a file, clone disks.
diskutil - Disk utilities - Format, Verify, Repair.
ditto - Copy files and folders.
authopen(1), hdid(8), ioreg(8), drutil(1), msdos.util(8), hfs.util(8), diskarbitrationd(8), /System/Library/CoreServices/DiskImageMounter.app.
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