MacOS – Change “ignore ownership on this volume” from the command line for Mac OS X volume

hfs+macossparsebundle

(This question is a spin-off of another question I asked on this site.)

New images always ignore owner/group

When creating a new disk image from Disk Utility it is automatically mounted. If you then select the volume in Finder and press Cmd-I (for the info window) you will see this at the bottom of the window:

enter image description here

This means that file owners and groups will be ignored on this volume. This is very convenient for external drives being shared between machines with different user accounts on them. For a backup volume it is not a good idea as you would like to retain the owner/group information for the files backed up.

Change this from Finder

To change this, simply uncheck the checkbox and it will remembered after you eject and remount the image.

Change from command line (Terminal)

Instead of mounting the image from Finder, you can also mount it from the command line using this command (assuming the image is called testimage.sparsebundle):

$ hdiutil attach testimage.sparsebundle/

Still, owners are ignored on the volume. Adding the -owners on option is (almost) equivalent to unchecking the checkbox in the image above:

$ hdiutil attach -owners on testimage.sparsebundle/

However, after unmounting and remounting the volume from Finder (or from the command line without the -owners on option), the checkbox is checked again.

Does anybody know how to make this change persistent using a command-line call?

Best Answer

You use diskutil for that. See diskutil(1) under enableOwnership and disableOwnership. Note that this setting is specific to a particular operating system installation, since it is stored in /var/db/volinfo.database. I.e., if you copy the disk image to a new computer the setting won't persist, but it does persist across reboots, mounts, umounts, etc. all on a single computer.

Use diskutil to find the identifier, then change the option:

$ diskutil list
/dev/disk2
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            Disk Image             *41.0 MB    disk2
$ sudo diskutil enableOwnership disk2
File system user/group ownership enabled

Related Solutions

Mac – Repair Time Machine sparsebundle that will no longer mount

I have a write up on how to try and repair NAS-based sparsebundle errors on my blog. In summary:

hdiutil attach -nomount -noverify -noautofsck /Volumes/{name of your disk}/{name of}.sparsebundle

You will then see something like
```
/dev/diskx Apple_partition_scheme
/dev/diskxs1 Apple_partition_map
/dev/diskxs2 Apple_HFSX
```
Where x is the disk id for the external disk. x might be 2, 3, 4 or higher. You are interested in the one labeled Apple_HFSX or Apple_HFS.
fsck_hfs -drfy /dev/diskxs2 using whatever relevant device was located in Step 1.

Hopefully, you will eventually see

The Volume was repaired successfully
hdiutil detach /dev/diskxs2

However, since OS X 10.6.3, Time Machine will refuse to write to a destination volume that fails its verification. Even if the process above succeeds in recovering the backup, you may still need to remove the black marks that Time Machine wrote when it failed verification.

Unlock the sparsebundle

chflags -R nouchg /Volumes/{name of your disk}/{name of}.sparsebundle

Move it back to its original location

mv /Volumes/{name of your disk}/{name of}_YYYY-MM-DD.sparsebundle /Volumes/{name of your disk}/{name of}.sparsebundle

At the top level directory of the sparsebundle, edit the file com.apple.TimeMachine.MachineID.plist.

Remove

<key>RecoveryBackupDeclinedDate</key>
<date>{whatever-the-date}</date>

Change

<key>VerificationState</key>
<integer>2</integer>

<key>VerificationState</key>
<integer>0</integer>

MacOS – way to minimize open windows from the command line in OS X Lion

I agree that pretty much any solution you can get for the command line would have to rely on AppleScript. And your solution will work. However, rather than scripting System Events, which depends on UI events (actually moving your mouse and clicking) it's a much cleaner approach to script the application's window directly.

This way, if you move your mouse while the script is executing, it won't affect it. For minimizing all Firefox windows you could do something like:

tell application "Firefox" to set miniaturized of every window to true

The property is called miniaturized for Firefox and most OS X applications, but some third-party apps, like Google Chrome, call the property minimized, so if one doesn't work, the other should. This functionality is part of the Standard Suite that pretty much every AppleScript-able application has.

For applications that don't support AppleScript at all, you can fall back to your approach and use System Events to access the windows belonging to the application's specific process running on your machine.

If I were you, though, I'd try to rely on the application to minimize itself rather than through System Events where possible, as this will be much more reliable.