How to Use the Command 'hdiutil' (with examples)

The hdiutil command is a versatile utility for macOS users that facilitates the creation and management of disk images. Disk images are files that can emulate physical disks and are commonly used for software distribution, file backups, and data management. With hdiutil, users can mount and unmount these images, create new images, and more, all through the command line interface. This utility is particularly useful for advanced users who need to automate tasks or require additional control over their disk image operations.

Use case 1: Mount an Image

Code:

hdiutil attach path/to/image_file

Motivation:

Mounting a disk image is a fundamental operation for accessing the contents within the image file. This is especially useful when you have downloaded software distributed in a disk image format (like .dmg) and need to install or run it. By mounting the image, it appears as a drive on your desktop, making it easy to interact with the files it contains.

Explanation:

• hdiutil: The command being used, responsible for all operations related to disk images.
• attach: Specifies the operation to perform, which in this case is to mount (or “attach”) the disk image so that it can be accessed.
• path/to/image_file: The file path to the disk image that you want to mount. This should be replaced by the actual path to your image file.

Example Output:

/dev/disk2              GUID_partition_scheme           
/dev/disk2s1            Apple_HFS                       /Volumes/Image Name

This output indicates that the image was successfully mounted, displaying the device identifier /dev/disk2 and its mounted volume /Volumes/Image Name.

Use case 2: Unmount an Image

Code:

hdiutil detach /Volumes/volume_file

Motivation:

Unmounting a disk image is necessary after you are done using its contents. This frees system resources and ensures that any changes within the image are properly saved. It also prevents data corruption that might occur if the system is shut down with the image still mounted.

Explanation:

• hdiutil: The utility in use to perform tasks on disk images.
• detach: This argument indicates the operation to unmount (or “detach”) the disk image, ceasing its representation as a drive.
• /Volumes/volume_file: The path to the mounted volume that you want to unmount. You need to replace this with the actual path to the specific mounted volume.

Example Output:

"disk2" unmounted.
"disk2" ejected.

This output shows that the operation succeeded, unmounting and ejecting the image identified as disk2.

Use case 3: List Mounted Images

Code:

hdiutil info

Motivation:

Listing mounted images is a convenient way to view all active disk images, especially when managing multiple images simultaneously. This can help identify which images are still in use, verify successful mounting, or aid in troubleshooting issues with specific volumes.

Explanation:

• hdiutil: The command used to manage disk images.
• info: This argument tells the utility to list information about all currently mounted disk images. No additional arguments are required for this operation.

Example Output:

/dev/disk2    /Volumes/Image Name   /path/to/image_file
/dev/disk3    /Volumes/AnotherImage /path/to/another_image

The output lists each mounted disk image along with its device identifier and volume path, making it easy to see what’s currently mounted.

Use case 4: Create an ISO Image from the Contents of a Directory

Code:

hdiutil makehybrid -o path/to/output_file path/to/directory

Motivation:

Creating an ISO image from a directory is useful for distributing a collection of files in a portable and platform-independent format. ISO images are particularly advantageous for software developers and IT professionals who need to share large sets of files across different operating systems, as they can be easily burned to optical media or mounted as virtual drives.

Explanation:

• hdiutil: The command used to handle disk images.
• makehybrid: This argument specifies the operation to create a hybrid image that is compatible across multiple platforms, often used for creating ISO files.
• -o path/to/output_file: This option indicates the output file path where the ISO image will be saved. You should replace this with the desired path and filename for your ISO.
• path/to/directory: The directory containing the files you want to incorporate into the ISO image. Replace this with the specific path to your directory.

Example Output:

Creating hybrid image...
Size of template: 12345678 bytes (12.3 MB)
Writing track 0...
...finished with status: 0

This output demonstrates the creation of the hybrid image, confirming the operation was successful and indicating the size of the resulting ISO file.

Conclusion:

The hdiutil command is a powerful tool for managing disk images on macOS, offering diverse functionalities to mount, unmount, inspect, and create images. By understanding these use cases and effectively utilizing hdiutil, users can streamline disk operations, enhance productivity, and ensure robust data management practices.