As I mentioned in my December 31, 2012 article, "How to Locate & Manage Your 'Stuff' in OS X", the Shared Folder is a special folder located inside the Users Folder in the system drive's root directory. One way to get to it is via the Finder's menu Go > Computer then opening your system drive (typically named "Macintosh HD") and finally into the Users Folder. There, you'll see the Shared Folder.
OS X creates the Shared folder when there are more than one user accounts on a Mac. It exists specifically to allow sharing of files *between user accounts* on any one Mac.
Why would you want to use the Shared Folder?
A great example of when utilizing the Shared Folder is quite practical is in situations where family members – each with his or her own account – want to share documents, images, videos and music files – whatever the case may be. This avoids excessive replication of files and file version confusion.
Let me tell you how I use the Shared Folder – doing so might just give you some ideas.
I create a user account on my MacBook Pro for each course that I teach. For example, for my iPhoneography course, a user account is created on my Mac, and it is named, quite imaginatively, iPhoneography.
Here's my preferred workflow for managing my instruction files:
I create my Keynote presentations and Pages handouts in my main working account, and I keep all my files organized in my DropBox folder (referring to the service offered by Dropbox.com). I then place copies of the files inside the Shared Folder (using the OPTION-DRAG method). Within the Shared Folder, I create folders for each course. The files are moved and organized into the appropriate course folders.
When in class, I log into the appropriate course account. For each account, I have already placed an alias of that course account's folder – the one that resides within the Shared Folder – onto my Finder Window sidebar as well as one sitting on the desktop in the lower-right quadrant. These aliases allow me to quickly drill-down into the Shared Folder. From there, I run my Keynote presentations directly, I open any Pages and/or PDF files I need to show for reference, or launch any Safari website shortcut files as needed. This is all pretty simple; not to mention a huge time saver.
You might be wondering why I bother using separate accounts for each course when I could just as well do everything from one account. I have a few reasons for managing my course materials this way.
Foremost in my mind is that I don't want the students to see my messy desktop! It's all about, "do as I say, not as I do." Yes, I know there are little utilities that address this, but doing so just adds another level of complexity. Additionally, by using a separate account during my lectures, I won't see (and hear) the various beeps and bops from text messages, email, tweets and other notifications that pop-up to distract the audience.
I also like to modify the desktop background in order to personalize it for the specific classes ... a welcome message, the name of the course, different colors, school logos ... you know, distracting stuff like that.
Finally, by using separate course accounts, I am free to modify system settings or whatever I need in order to facilitate my instruction without impacting any settings and preferences back in my main working account.
At the end of the semester, I simply delete the course accounts with a couple of clicks. I'm not concerned about any files as I don't create any content that needs to be kept during the course. I still have my original course files in my Dropbox folder back in my working account.
And now: the question of File Permissions. Permissions – also referred to as Privileges – are part of the underlying UNIX system that, among other things, determine which user account owns which files and folders, what that user is permitted to do to the files, as well as what permissions other accounts have regarding their use of your files and folders.
A discussion of OS X file permissions can get quite geeky – and therefore, rather involved. Fortunately, Apple gives us a simple interface for managing some permissions settings. I am going to keep this basic because there are many combinations of permissions settings for various scenarios. I can tell you, however, that just keeping permission settings in their default states is still quite useful.
Go to your Shared Folder, take a look at the default permissions for that folder. To do this, first select the folder, and then going to File > Get Info. Direct your attention to the very bottom section of the Get Info panel; the section named Sharing & Permissions. We'll ignore the permissions for the special built-in users called "system" and "wheel" and possibly "Staff." But I will strongly advise you now to NOT mess with permissions for those users!
The Get Info panel is the starting place for the setting of file and folder permissions.
Notice the "everyone" user group designation. By default, every user account has full Read and Write permissions. Basically, this gives every user account the right to go into the Shared Folder and create files and folders. Everyone can also read files owned by other users, and open folders owned by others, unless the permissions are modified by the other accounts to close down their own files/folders. However, this would be contrary to the purpose of utilizing the Shared Folder. A user who doesn't intend to share his files, should store them inside his own Home Folder. Refer to the article referenced above for more information on using the Home Folder.
Incidentally, it's important to note that "everyone" includes other users on the network, if you have set your Sharing System Settings to allow this.
Assuming that permissions settings are kept unchanged, when a user creates and/or places a file or folder inside the Shared Folder, that user is the "owner" of the item. By default, the owner will always have Read & Write permissions assigned to those items. If a user drags one of his files or folders to the Shared Folder, those items MOVE (as opposed to COPY) because, again by default, every user account has Read & Write permissions on the Shared Folder. In this case, the Shared Folder behaves like any other folder with respect to how files can be moved and copied.
Because, by default, other users are given Read Only permission for all but their own files and folders, those users are able to open and read files, and to open folders, that belong to other user accounts. However, "Read Only" means that there can be no modifications or deletions except to ones own files and folders.
A user can drag another user's file or folder to his own desktop, in which case the file/folder will be COPIED (as opposed to MOVED). From this point on, the copy will be owned by this user.
If, within the Shared Folder, one user attempts to modify or delete a file or folder belonging to another user, OS X will display a warning and a request authentication.
Returning to my teaching scenario. To make things easier for myself, and because I am the only person who uses this MacBook Pro, there is a very practical change I make to the permissions settings. Let me explain.
As already mentioned, on my Mac I have assigned a distinct user account for each of my courses. They are all Admin accounts. In OS X, there is a special built-in group account called Administrators. I can add this special Administrators account to the list of names in the Sharing & Permissions section of the Get Info panel. I then assign Read & Write permissions to the Administrators account where needed. Since all accounts in question are Admin accounts, they all enjoy any permissions assigned to the Administrators group.
I add the Administrators Group to the list of users who have access to the contents of the Shared Folder. To do so, I first have to authenticate by clicking on the little lock at the bottom of the Get Info panel.
Clicking the lock icon will result in an authentication prompt. The icon will then display its unlocked status.
Next, I click on the little '+' sign below the Name column, indicating my intent to add a user and having Shared Folder permissions assigned to that user. From the resulting pane, I select Administrators.
The Administrators user group is built-in to OS X.
Then, I need to change the permissions for Administrators from the default Read Only to Read & Write.
You are able to change privileges from Read only to Read & Write.
Finally, by clicking on the little gear icon at the bottom-left, I select "Apply to Enclosed Items" from the pop-up menu.
Selecting "Apply to enclosed items" will propagate down into the Shared Folder contents all the permission settings seen here.
This will propagate the listed Sharing and Permissions settings, including those for the newly-added Administrators group, down into the Shared Folder and assign them to all, including nested, files and folders. The idea is to simply give all my course user accounts equal permissions on everything in the Shared Folder. As long as I have my original files safely stored within my Home Folder, and therefore in my Dropbox folder, I'm not concerned about what happens to the files in the Shared Folder.
In conclusion, you may find yourself in a situation like mine, where you teach different classes, or perhaps you demo software to various groups. You may even have several family members who share a Mac at home. Why not explore the potential usefulness of the Shared Folder? Setting it up in multi-user situations will, at the very least, cut down on the frustrations inherent to the sharing of files and data.