In This Chapter
Now here's a topic that MacBook power users can sink their teeth into — the idea that a document on a multiuser system can be everyone's property, allowing anyone in your family, workgroup, or highly competitive mob to make whatever changes are necessary, whenever they like.
Of course, potential pitfalls lurk — even in the Apple world, there's no such thing as an operating system that's both powerful and perfectly simple. However, I think you'll find that our dear friends from Cupertino have done just about as well as can be expected and that the settings that you use to share documents are fairly easy to understand and use.
Prepare to share!
First, allow me to clear up what I've found to be a common misconception by using another of Mark's Maxims.
Note
Sharing documents on a single computer is fundamentally different from the file sharing that you've used on a network.
True, multiple users can share a document over a network, which is a topic that I cover in Book VII. But although the results are the same, the way that you share that same document on a single machine betwixt multiple users is a completely different turn of the screw. In this section, I discuss the factoids behind the matter.
Although reiterating that no network is required is seemingly the most obvious of statements, many otherwise knowledgeable Mac OS X power users seem to forget that sharing a document over a network requires an active network connection. (Note the word active there.) Unless you physically copy the document to your hard drive — which defeats the purpose of document sharing — any loss of network connectivity or any problem with your network account will result in a brick wall and a brightly painted sign reading, "No luck, Jack." (Or perhaps it's flashing neon.)
On the other hand, a document shared on a multiuser MacBook in the home or classroom is available whenever you need it. As long as the file is located in the Shared folder, the file privileges are set correctly, and you know the password (if one is required by the application, such as a password-protected Word document), then — as they say on "Star Trek" — "You have the conn" whether your network connection is active or not.
Sharing documents over a network can get a tad hairy when multiple users open and edit the document simultaneously. Many applications, such as Office 2008 for the Mac, have methods of locking the document (giving one person exclusive access) when someone opens it or saves it. However, you always face the possibility that what you're seeing in a shared network document isn't exactly what's in the document at that moment.
A multiuser system doesn't need such exquisite complexity. You're the one sitting at the keyboard, and you have control: This is what network administrators call a guaranteed lock on that document file. Refreshing, isn't it?
But wait! Mac OS X Snow Leopard includes a feature called Fast User Switching — I discuss it in Book II, Chapter 2 — that allows other users to remain logged in behind the scenes while another user is at the keyboard. Therefore, if you enable Fast User Switching, two users could have the same document open at the same time. To prevent this, you can simply turn off Fast User Switching from the Accounts pane in System Preferences. (Click Accounts, click Login Options, and clear the Enable Fast User Switching check box.)
Network users are often confident that they can blithely copy and move a document from one place to another with the greatest of ease, and that's true. Most shared network documents created by an application — such as a project outline created in Word, for example — carry their own sharing information and document settings internally. Thus, you can move that same file to another folder on your hard drive, and the rest of the network team can still open it. (Um, if they have the network rights to access the new folder, of course.)
This isn't the case when it comes to multiuser documents. As you can read in Chapters 4 and 5 of this minibook, Mac OS X places a rather tight fence around a standard-level user, allowing that person to access only the contents of certain folders. In this case, your document must be placed in the Shared folder for every standard-level user to be able to open it. (Alternatively, the document can be stored on an external hard drive, allowing every user account on your system to access it.) If everyone using the document has administrator access, you can store the file in other spots on your system; as long as the permissions are set, you're set. And speaking of permissions ...
Files are shared in Mac OS X according to a set of rules called permissions, the ownership of the file (typically the person who saved the document the first time), and an access level specified as a group. The combination of privileges, ownership, and group determines who can do what with the file.
When you (or the person with the administrator account on your MacBook) created your user account, you were automatically granted ownership of your Home folder and everything that it contains as well as any files or folders that you store in the Shared folder or another user's Public folder.
Four possible actions are allowed through permissions:
Read Only: This action allows the user to open and read the file, which includes copying it to another location.
Read & Write: This permission grants full access to the file, including opening, reading, editing, saving, and deleting. Read & Write permission also allows the user to copy or move the file to another location.
Write Only (Drop Box): A neat permission setting that appears only with a folder — it allows access to copy an item to the folder, but not to read any files it contains. (Hence the informal name Drop Box, and the + [plus sign] icon added to the folder's icon to identify it.) For example, a drop box is made to order for teachers: Students can submit homework by dragging their work to the teacher's drop box.
No Access: This is just what it sounds like — the user can't open the file, copy it, or move it.
Warning
No matter what permissions you've set, only the System Administrator (or root user) can copy items into another user's Home folder using the Finder. Take my word for it on this one: Simply consider that this can't be done, and stay as far away from the Root/System Administrator account as possible. (I repeat: Trust me on this.) Read all about the perils of enabling the System Administrator account in Chapter 4 of this minibook.
These permissions are set in the Info dialog for a file or folder (always accessible by pressing
To set permissions, follow these steps:
Click the item to select it, press
If you have a mouse or trackball with a right button, you can right-click the item and choose Get Info instead. Either way, Mac OS X displays the Info dialog.
Click the right-facing arrow next to the Sharing & Permissions heading to expand it, as shown in Figure 6-1.
Because I selected a folder, the Apply Enclosed Items button appears at the bottom of the section.
To change your own permissions on the item, click the Privilege pop-up menu and choose a new Ownership permissions level.
This is likely set to Read & Write, and it's a good idea to leave it alone. If you're the file's owner, you're likely not a security risk.
Warning
Perhaps I should be a little less tactful here: Never choose an access level for yourself other than Read & Write without being absolutely sure of what you're doing, because you can potentially prevent yourself from accessing or deleting the file in the future! For example, if you simply want to lock an item to prevent changes being made, don't set your Ownership permission to Read Only. (Instead, select the Locked check box in the General section of the Info dialog instead ...you can easily clear the Locked check box later to make changes to the item.)
To change permissions for someone else or a group, click the Privilege value for that user or group and then choose the appropriate value from the pop-up menu.
Tip
Assigning permissions for an entire group is a good idea for limiting specific files and folders to only Administrator access. (Note, however, that Snow Leopard reserves the group name wheel for internal tasks, so never alter any permissions for the wheel group.)
If necessary, set the permission for the Everyone pop-up menu (otherwise known as "I'm going to lump everyone else into this category").
If a user isn't the owner of an item and doesn't fit into any group that you've selected, this access permission setting for this file applies to that user.
If you're setting permissions for a folder, Snow Leopard can automatically change the permissions for all the items contained in the folder to the same settings. Click the Action pop-up menu button at the bottom of the Info dialog (which bears a gear symbol) and choose Apply to Enclosed Items. Mac OS X displays a confirmation dialog.
Warning
Generally, it's a good idea not to override the permissions for all the items in a folder, so use the Apply to Enclosed Items function only when necessary.
After all the permissions are correct, click the Close button to save your changes and return to your friendly Finder.
If a specific user or group doesn't appear already in the Privilege list, click the Add button (bearing the plus sign) and you can add a specific privilege level for that user or group. You can also delete a privilege level: Click the desired entry to select it and click the Delete button (which bears a minus sign).
After you get the basics of sharing files and assigning permissions under your belt, you need to master when to change permissions and why you should (and shouldn't) modify them. Follow these common-sense guidelines when saving documents, assigning permissions, and choosing access levels:
Do use your Shared folder. The Shared folder is the center of proper document sharing. I know there's a strong urge to create a new document in your Home folder, but you're just making more work for yourself because you'll end up copying that document from your Home folder to the Shared folder. Instead of an extra step, store a document that's intended to be shared in the Shared folder — where it belongs in the first place.
Don't assign permissions just to protect a file from deletion. Remember, if all you need to do is prevent anyone (including yourself) from deleting an item, you don't need to go to all the trouble of changing permissions. Instead, just display the Info dialog for the item and select the Locked check box to enable it, which prevents the item from being deleted from the Trash until the Lock status is disabled.
Do review the contents of a folder before changing permissions for enclosed items. That confirmation dialog doesn't appear just for kicks. For example, if you set a highly sensitive, private document with permissions of No Access for everyone but yourself and then you apply less-restrictive permissions globally to the folder that contains the document, you've just removed the No Access permissions, and anyone can open your dirty laundry. (Ouch.) Therefore, make sure that you open the folder and double-check its contents first before applying global permissions to the items it contains.
Don't change permissions in the Applications or Utilities folders. If you have Administrator-level access, you can actually change the permissions for important applications such as Mail, Address Book, iTunes, and Safari, as well as their support files. This spells havoc for all users assigned to the standard-access level. Be polite and leave the permissions for these files alone.
Definitely don't change System ownership. Mac OS X is stable and reliable. Part of that stability comes from the protected state of the System folder, as well as a number of other folders on your hard drive. If you displayed the Info dialog for the System folder, you'll see that the Owner is set to system, and the Group is set to wheel (a term from the UNIX world that encompasses all administrator accounts). Now, promptly close that Info dialog, without making any changes!
Never, never, NEVER change any permissions for any files owned by the System unless specifically told to do so by an Apple support technician. Do NOT monkey with System-owned items.
This last one is quite striking for a reason, so please heed the warning.
Many Mac OS X applications offer their own built-in document-sharing features. For example, Microsoft Office 2008 for the Mac includes both file-level and document-sharing features. Because Office 2008 is currently the most popular productivity suite available for Mac OS X, I discuss these commands in this final section.
You'll find a number of commands that help multiple users keep track of changes that have been made in a shared Office document. Probably the most familiar is the Word revision tracking features (heavily used during the development of this book), but there are others as well:
Revision marks: If several users edit a document, how can you tell who did what? By using revision marks, which apply different colors to changes made by different editors, those additions and deletions can be accepted or rejected individually at a later date. If Johnson in Marketing adds incorrect material, you can easily remove just his changes. In a worst-case scenario, you can actually reject all changes and return the document to its pristine condition.
Compare Documents: Using this feature allows you to compare a revised document with the original (if, of course, you still have the original file handy). I use Compare Documents only if revision marks weren't turned on before editing began.
Comments: Editors can also converse within a document by using embedded Comments. These don't change the contents of the Word file the way revision marks do, but store commentary and notes in a behind-the-scenes kind of way. (Think of a Mac OS X Sticky that appears within a document.) Again, the author of each comment is listed, allowing for (sometimes heated) communication within the body of a document.
Highlighting: You've heard the old joke about ...Well, anyway, a traditional highlighter marker is pretty useless on a computer monitor (leaving a nasty mess for the next user to clean), but Word allows multiple highlighting colors for identifying text. (And for the occasional practical joke — nothing like adding eight different highlighting colors to that important proposal. Just make sure that your résumé is up-to-date.)
Along with the document-level sharing commands, you'll find that Office 2008 applications also offer sharing features that control access to the document file itself.
You can add password protection to any Office 2008 document. Follow these steps with a document created within Word, Excel, or PowerPoint:
Choose File
In the Save As dialog that appears, click Options to display the Save Preferences pane.
Click the Show All toolbar button.
Click Security to display the Preferences pane that you see in Figure 6-2.
To password-protect the document, enter a password in the Password to Open field.
Note
This password must be provided when opening the document.
If you like, you can enter another password in the Password to Modify field. This second password would then also be required to modify the document.
Tip
Both passwords are case sensitive.
Click OK to save the preference changes and return to your document.
Think of the Protect Document dialog in Word, from which you can effectively write-protect certain elements, as an extra level of security in a multiuser environment. In this Office application, you can protect revision marks, comments, and sections of a document containing forms. A password can be added if desired. To display the Protect Document dialog, click Tools in any of the Office 2008 applications and choose Protect Document from the pop-up menu that appears.