How to Access Mac Filesystem from Xubuntu

macmacosxpartitioningxubuntu

I have a macbook pro with 2 OS's… Mac OSx and Xubuntu (newest release.)

I have followed a lifehacker guide on allowing access of my OSx partition when booted into my linux OS which included changing the linux uID, and disabling Journaling on my HFS+ drive.

I see my OSx partition when booted in linux in my file browser, but when I go into it deeper, I get 'Access Denied.' I see that, in OSx's disk utility, i have the option to disable encrypting, but when I hit it, nothing changes… Would that encryption be interfering?

Any ideas?

Best Answer

The problem isn't encryption, it's file permissions. IIRC, OS X gives its default user a user ID (UID) of 501, whereas in Ubuntu the first user's UID is 1000. Thus, the files on the disk appear to be owned by somebody other than you, which means you'll have no access to those files as anything but root.

You can change the UID of your OS X user or of your Linux user. For Linux, you can use usermod to do this, but you'll need root privileges, and this is a bit awkward given the way Ubuntu sets things up unless you've got two accounts with administrative privileges. Also, using a UID that's lower than 1000 will create some (mostly minor) complications. See this question on this site for more on this topic. I'm not sure how you'd change your OS X UID to 1000, offhand; perhaps a Web search or asking on an OS X site will help.

I must question the wisdom of granting read/write access to your main OS X partition from Linux, though. This is asking for trouble, for three main reasons:

The Linux HFS+ driver, although pretty good, may have bugs that could cause data loss. If you run into such bugs, the mere act of mounting the OS X volume in Linux could trash all the data on that partition. I'd like to emphasize that I don't know that such bugs actually exist, but they might.
By disabling the journal on the HFS+ volume, you'll increase filesystem check times, which could slow down the boot process if OS X needs to run a filesystem check.
Linux doesn't include explicit safeguards against damaging OS X system files. Although ordinary file permissions should help, an accident as root in Linux could trash the OS X system.

Similar comments apply to accessing the Linux partition from OS X, too, although you might not need to disable a journal to do the job. (I haven't checked the latest status of OS X's Linux filesystem drivers on this score.)

Instead of mounting your OS X root (/) partition in Linux with read-write access, it's probably better to create a separate data-exchange partition. If you don't need to exchange big (over-4GiB) files, FAT will handle this task quite well, and using FAT will bypass the UID issues that are the root cause of your problem. So will NTFS, but unless you're triple-booting with Windows, using NTFS is inadvisable because there are no good NTFS repair tools in OS X or Linux, so sooner or later an NTFS volume would become inaccessible. Thus, if FAT is inadequate, a separate HFS+ volume is probably best. You'd then need to either synchronize your UID values or set very permissive permissions on the directories you use in the file-exchange partition (including its root directory).

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You need a theme for XFCE, Xubuntu's desktop enviroment.

Look around on http://xfce-look.org/

This one looks nice:

http://xfce-look.org/content/show.php/Cratos-lion?content=151866

Ubuntu – Trouble Accessing Mac OS X Partition from Ubuntu 14.04

If you have gone and changed your uid and gid, go and change them back now before even going past this first part of this answer.

Unless you really know what you're doing, you should NEVER go change your uid or gid just to mount a drive, as you can break other permissions in the computer and potentially lose access to your own home directory in the Linux partition.

Usually when you mount a drive, you pass arguments to provide the uid and gid as options for the mount to specify user/group ownership, as well as other important permission mask arguments, and other arguments (this is most typically done with vfat or ntfs partitions, but it applies to most partition types, especially ones which don't respect the Linux permissions systems). While this is usually done as part of the /etc/fstab file for persistent options for specific partitions or media, you can manually provide options for a given mount command if you wish.

Mounting with the following command should do what you need it to do without modifying your own user's UID or GID. This makes a MacOS folder in /media/username/, where we'll mount the drive partition to:

sudo mkdir -R /media/username/MacOS
sudo chown --recursive username:username /media/username
sudo mount -t hfsplus -o uid=USERUID,gid=USERGID /dev/sdx /media/username/MacOS

Replace /dev/sdx with the actual partition identifier, and all instances of 'username' with the user's name. Similarly, replace USERID and USERGID with the actual values there.

To make it persistently user mountable, you should add an fstab entry that allows users to mount and unmount the drive, while providing the uid and gid accordingly.

(Note: the uid and gid arguments were obtained from kernel.org documentation. You must have the prerequisite libraries to read hfsplus partitions to make this work.)

Best Answer

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