The macOS command-line tool hdiutil is used to manipulate disk images. From the WHAT'S NEW section of man hdiutil on the latest macOS 27 Golden Gate beta:
In macOS 27.0, hdiutil is deprecated. Use diskutil image instead for all disk image operations. diskutil image provides subcommands for attach, create, resize, info, and chpass. ASIF (Apple Sparse Image Format) images are only supported by diskutil image and are not supported by hdiutil.
There’s also a DEPRECATION NOTICE at the top of the man page that lists the diskutil replacements for hdiutil subcommands.
The majority of options from hdiutil appear to be preserved in diskutil, though under different names. However, some hdiutil options are missing, for example -puppetstrings:
provide progress output that is easy for another program to parse. PERCENTAGE outputs can include the value -1 which means hdiutil is performing an operation that will take an indeterminate amount of time to complete. Any program trying to interpret hdiutil's progress should use -puppetstrings.
Also missing are some options specific to hdiutil create -srcfolder:
-[no]crossdev
-[no]scrub
-[no]anyowners
-skipunreadable
-[no]atomic
-copyuidI attempted to compare hdiutil and diskutil on Golden Gate by performing a backup of the user home folder, something I do daily on my MacBook Pro with macOS Sequoia. First:
time hdiutil create -encryption -format UDZO -noatomic -noscrub -srcfolder /Users/stupiduser -stdinpass -verbose /Users/Shared/hdiutil.dmgThis took around 110 to 115 seconds on average.
It’s crucial to note that hdiutil triggers an authentication prompt, because one of the files is, annoyingly, owned by the root user. From the Terminal output:
copy-helper[2598:97396] uid 501 does not have ownership of /Users/stupiduser/ Library/ Group Containers/ group.com.apple.secure-control-center-preferences/ Library/ Preferences/ group.com.apple.secure-control-center-preferences.av.plist - setting needAuth to YES
Scanning…
Error 80 (Authentication error).
/Users/stupiduser/ Library/ Group Containers/ group.com.apple.secure-control-center-preferences/ Library/ Preferences/ group.com.apple.secure-control-center-preferences.av.plist: Authentication error
The disk image creation continues and finishes successfully after authenticating with admin credentials.
Now the new method:
time diskutil image --stdinpassphrase --verbose create --encrypt from --format UDZO /Users/stupiduser /Users/Shared/diskutil.dmgThis simply fails and, despite the verbose option, doesn’t tell you why.
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Error: Failed to create disk image: The operation couldn’t be completed. Operation not permittedLuckily, I guessed the reason, the root-owned file. Unlike hdiutil, diskutil does not trigger an authentication prompt. Thus, I had to delete the root-owned file to get diskutil to work.
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/Users/Shared/diskutil.dmg createdAgain, not particularly verbose. However, the progress percentage does update in place during the disk image creation, so there is some kind of substitute for the hdiutil -puppetstrings option.
The good news is that diskutil was significantly faster, taking around 40 to 45 seconds on average to finish, more than a minute faster than hdiutil. Also, the resulting dmg file from diskutil was smaller, 2.8 GB, as opposed to 2.89 GB from hdiutil.
I mounted the two disk images and used the FileMerge app (embedded inside the Xcode app) to compare them. Aside from a few files that were naturally modified in the few minutes between the two command-line invocations, the main difference was that the hdiutil disk image included the ~/.Trash/ folder, while the diskutil disk image did not. In other words, diskutil behaved as if the -scrub option of hdiutil were enabled.
-[no]scrub do [not] skip temporary files when imaging a volume. Scrubbing is the default when the source is the root of a mounted volume. Scrubbed items include trashes, temporary directories, swap files, etc.
So it appears that diskutil in Golden Gate needs some work:
-[no]scrub optionTo conclude, I don’t understand why hdiutil needs to be deprecated when the same functionality will live on in diskutil. For some reason, Apple seems intent on breaking longtime workflows and scripts. Many years ago I actually worked on an app, Knox, that calls hdiutil directly. If hdiutil were removed from macOS, that would completely break such an app.
By the way, both hdiutil and diskutil on Golden Gate still suffer from the bug I blogged about last year, Inaccessible .bnnsir files on macOS Sequoia. A couple days ago I got a ridiculous update to the bug report I filed with Apple, “hdiutil create copy error with Siri CoreSpeech .bnnsir files” (FB17162985). Despite giving Apple 100% reliable steps to reproduce, they asked me if the issue still occurred in the latest beta, and if it does, then I should submit an iOS sysdiagnose. Yes, Apple requested an iOS sysdiagnose for a macOS bug. And needless to say, the latest Golden Gate beta did not magically fix the bug.