Data Management and Backup

Applications—Often called the local Applications folder, this is the default location for applications available to all local users. Only administrative users can make changes to the contents of this folder.

Often called the local Library folder, this is the default location for ancillary system and application resources available to all local users. Once again, only administrative users can make changes to the contents of this folder.

This folder contains resources required by the operating system for primary functionality. Users very rarely have to make changes to the contents of this folder. Even administrative users are unable to make changes to items in the System folder without reauthenticating.

This is the default location for local user home folders. Specific access to home folder items is discussed in Chapter 2, “User Accounts.”

Developer (Optional)—This optional folder contains the Apple Xcode Developer Tools. This is not part of the standard installation, but it’s still a fundamental part of the system, and its installer can be found on the Mac OS X Install DVD. Similar to the Applications and Library folders, the Developer folder can be changed only by an administrative user.

Within the various Library folders throughout the system volume.

• System resources can be generally categorized as any resource that is not a general-use application or user file.
• That’s not to say that applications and user data can’t be found in the Library folders. On the contrary, the Library folder is to keep both user and system resources organized and separated from the items you use every day. This keeps the Applications folder and user home folders free from system resource clutter.

This folder can be found in both the user and local Libraries. Any ancillary data needed by an application may end up in this folder. For example, it often contains help files or templates for an application. Once again, application resources are placed here to keep the Applications folders tidy.

Extensions—Also called kernel extensions, these items are found only in the system and local Library folders. Extensions are low-level drivers that attach themselves to the kernel, or core, of the operating system. Extensions provide driver support for hardware, networking, and peripherals. Extensions load and unload automatically, so there is little need to manage them, as is common in other operating systems. Extensions are covered to greater detail in Chapter 9, “Peripherals and Printing.”

Fonts—Found in every Library folder, fonts are files that describe typefaces used for both screen display and printing. Font management is covered in the “Managing Font Resources” section later in this chapter.

Found in every Library folder, frameworks are repositories of shared code used among different parts of the operating system or applications. Frameworks are similar to extensions in that they load and unload automatically, so again there is little need to manage these shared code resources. You can view your Mac’s currently loaded frameworks from the /Applications/Utilities/System Profiler application.

Keychains—Found in every Library folder, keychains are used to securely store sensitive information, including passwords, certificates, keys, website forms, and notes. Keychain technology is covered previously in Chapter 2, “User Accounts.”

LaunchDaemons and LaunchAgents—These items can both be found in the local and system Libraries, and LaunchAgents can also be found in the user’s library. These Launch items are used to define processes that start automatically via the launchd process. Mac OS X uses many background processes, which are all started by launchd. Furthermore, every single process is a child of the launchd process. LaunchAgents are for processes that need to start up only when a user is logged in, whereas LaunchDaemons are used to start processes that will always run in the background even when there are no users logged in. More about launchd can be found in Chapter 10, “System Startup.”

Logs—Many system processes and applications archive progress or error messages to log files. Log files can be found in every local Library folder. Log files are viewed using the /Applications/Utilities/Console application.

PreferencePanes—PreferencePanes can be found in any Library folder. These items are used by the System Preferences application to provide interfaces for system configuration. System Preferences usage is covered in Chapter 1, “Installation and Initial Setup.”

Preferences—Preferences, found in both local and user libraries, are used to store system and application configuration settings. In other words, every time you configure a setting for any application or system function, it is saved to a preference file. Because preferences play such a critical role in system functionality, they are often the cause of software problems. Troubleshooting preference files is covered in Chapter 6, “Applications and Boot Camp.”

Startup Items—Startup Items, found in only the local and system Libraries, are precursors to LaunchAgents and LaunchDaemons. Starting with Mac OS X 10.5, Apple is officially discouraging the use of Startup Items. In fact, you will have Startup Items only if you’ve installed third-party software that hasn’t been updated. In Mac OS X 10.6 the launchd process will still support many Startup Items, but this will probably not be true for future versions.

User Each user has his own Library folder in his home folder for resources. When resources are placed here, only the user has access to them. Also, a user can have his own Applications folder in his home folder.

Local Both the root Applications and root Library folders are part of the local resource domain. This is why they are known as the local Applications and local Library folders. Any resources placed in these two folders are available to all local user accounts. By default, only administrative users can make changes to local resources.

• Network Mac OS X can access system resources and applications from a network file share. Administrators must configure an automounted share in order to enable the Network resource domain. Configuring automounted shares goes beyond the scope of this guide. However, it is covered in another reference guide, Apple Training Series: Mac OS X Server Essentials v10.6.

System Finally, the system domain encompasses all the items necessary to provide core system functionality. There are many hidden items at the root of the system volume that make up the system resource domain, but the only one you will see in the Finder is the root System folder. In many cases, you do not need to add or manage any resources here.

Extensions

Extensions provide driver support for hard- ware, networking, and peripherals. Extensions load and unload automatically, so there is little need to manage them, as is common in other operating systems.

Launch items are used to define processes that start automatically via the launchd process

With four different domains containing resources, there is a strong likelihood for overlap in resources, meaning there may be multiple copies of similar resources available to the system and user at any given time. The system is designed to handle this by searching for resources from the most specific, those in the user domain, to the least specific, those in the system domain. If multiple similar resources are discovered, the system will use the resource most specific to the user.

third party app

• In the users font library.
• If you are an admin the choice is given to you to install in the local library (local being the machine).

It will validate it to see if the font is compromised.

Clicking on the diable fonts button in font book

In font book go to Edit > Resolve Duplicates

Command-A keyboard combination to select all the fonts. Choose File > Validate Fonts to start the validation process.

• You have to do it via the command line.
• To hide you type:
• chflags hidden filename

• to unhide
• chflags nohidden filename

Aliases—These shortcuts are a holdover from the classic Mac OS but have been updated for Mac OS X duties. Aliases can be created with the Finder but are useless in the command line. Command line tools think that aliases are nothing more than data files and do not know how to follow their references back to the original items. Aliases, however, are more resilient than other shortcut types in that if the original item is replaced or moved, the alias will almost never lose the original item.

• Symbolic Links—These shortcuts are part of the traditional UNIX file system and are simple pointers to the file system path of the original item. Thus, if you move the original item, the symbolic link will be broken. However, replacing the original item
• works because the path remains the same. You can create symbolic links with the ln command. The Finder cannot create symbolic links, but it can follow them to the original item. An example use of symbolic links in Mac OS X is the way the system
• layout stores several fundamental UNIX folders in the /private folder but also makes those items available at the root of the file system using symbolic links.

Hard Links—These shortcuts are also part of the traditional UNIX file system and are actual additional references to the original item. Think of a normal file as two parts; first, the bits on the physical drive that make up the file’s actual content, and second, a name that points to those bits. A hard link is an additional name that points to the same bits on the physical drive. You can also use the ln command to create hard links. The Finder cannot create hard links, but it can follow them. An example use of hard links in Mac OS X is for Time Machine backups. Time Machine uses hard links to reference items that have not changed since the previous backup, thus saving a tremendous amount of space. Finally, Mac OS X is unique in its ability to use hard links of both files and folders; again, this is to support Time Machine backups.

• Ctrl L
• from finder window click on gear
• Right click, make alias
• From finder File > Make Alias
• Click and drag the original item while holding down the Option and Command keys to drop an alias in another location. This is the only method that doesn’t append the word “alias” to the new alias filename.

The original item has to remain on the original volume. The original can be renamed as well.

Show you the original item.

You will be presented with an opportunity to fix the alias.

• ln creates a hardlink
• ln -s creates a symbolic link

ln -s MyFolder MyFolderSymLink

F and F

Removing additional hard links will not delete the original item. Furthermore, deleting the original item will not delete the hard links; they still point to the same bits on the disk, which won’t be freed until there are no links left to them.

The same bits on the physical drive.

To describe data.

names, paths, modification dates, and permissions.

• Executable code for multiple platforms
• Document description files
• Media resources such as images and sounds
• User interface description files
• Text resources
• Resource forks
• Resources localized for specific languages
• Private software libraries and frameworks
• Plug-ins or other software to expand capability

Right click > show package contents

Launch Services identifies the file based on its type and then references an application registration database to determine which application should open the file.

just to local user

• com.apple.LaunchServices.plist
• ~/Library/Preferences folder

Hold down option and choose always open with

• Quick Look is able to preview an ever-growing variety of file types using a plug-in technology.
• Each Quick Look plug-in is designed to preview specific types of files. Many Quick Look plug-ins are included by default, but Apple and third-party developers can create additional plug-ins to expand Quick Look’s preview capabilities. Included Quick Look plug-ins enable you to:

Preview any audio or video file that can be decoded by QuickTime

• Preview a variety of graphics files, including many digital camera files, PDF files, EPS
• files, and any standard graphics file

Preview a variety of productivity files including standard text files, script files, and files created by the iWork and Microsoft Office suites

• Quick Look plug-ins, like any other system resource, are stored inside the various Library
• folders. Preview a variety of Internet-centric files including mailboxes, iChat transcripts, and web archives

Yes. Local once it is ready to do so. External once they are attached

This does not include read only such as cd's

• False.
• Even though Spotlight indexes every item on a volume, it will automatically filter search results to show only items that the current user has permissions
• to access.

• Search via basic file metadata, including name, file size, creation date, and modification date
• Search via media-specific metadata from picture, music, and video files, includingtime code, creator information, and hardware capture information
• Search through the contents of a variety of file types, including text files, iLife related files and databases, Photoshop files, PDF files, iWork files, and Microsoft Office files
• Search through personal information like Address Book contacts and iCal calendar events
• Search for correspondence information like the contents of Mail emails and iChat chat transcripts
• Search for highly relevant information like your favorites or web browser bookmarks and history

By setting manually setting spotlight to ignore the volume

By adding and removing a volume once it has been indexed.

Disk images are files that contain entire virtual drives and volumes. Mac OS X relies on disk images for several core technologies, including software distribution, system imaging, NetBoot, FileVault, and network Time Machine backups. Disk images are also useful as a personal archive tool.

2TB

Image format—Disk images can be read-only or read/write. They can also be a set size or expandable as a sparse disk image. Sparse disk images will take up only as much space as necessary and automatically grow as you add items to them.

• Compression—Read-only disk images can be compressed to save space. With a compressed
• disk image, any free space becomes negligible in size, and most other files average a 50 percent reduction in size.

Encryption—Any disk image can be protected with a password and encrypted with strong 128-bit or 256-bit AES encryption. Choosing a higher bit rate is more secure but degrades performance. This feature is useful for securing data stored on otherwise unsecure volumes like removable drives and network shares. The encryption always happens on the local computer, so even if the disk image file is physically stored externally, as on a network file share, the data is always encrypted as it travels across the connection.

• File system—Disk images can contain any partition scheme or volume
• Mac OS X supports, including optical media formats. Details regarding
• between file system options are covered in Chapter 4, “File Systems.”

• Everything
• Volumes
• User Accounts

Sparse option from image format.

Disk Image can only make images of volumes that it can unmount temporarily.

You need about twice as much space. Once to create the image and a second time to compress the image.

Anything attached to the machine that isn't the primary drive.

It can't save large files over and over again. It will take up too much space. The changes won't stick regardless if changes are only a few bytes. It will recopy the entire file.

From the command line.

The metadata in the files.

The four default top-level folders visible in the Finder are: Applications, containing applications all local users have access to; Library, containing system resources all local users have access to; System, containing necessary system resources; and finally, Users, containing all the local user home folders.

Six common system resources are: extensions, which attach themselves to the system kernel to provide hardware and peripheral driver support; frameworks, which are shared code libraries that provide additional software resources for both applications and system processes; fonts; preference files, which contain application and system configuration information; LaunchAgents and LaunchDaemons, used by launchd to provide services that automatically start when they are needed or at system startup; and finally, logs, which are text files that contain error and progress entries from nearly any application or system service.

• The four system resource domains are: User, containing applications and system
• resources specific to each user account; Local, containing applications and system resources available to all users on the local Mac; Network (optional), containing applications and system resources available to any Mac that has an automated network share; and finally, System, containing applications and system resources required to provide basic system functionality.

The Finder hides traditional UNIX resources from average users because they don’t need to have access to those items. If users do need access to these UNIX items, they can access them from the Terminal.

The Finder will not show items with periods at the beginning of their filename, or items with the hidden file flag enabled.

Resource forks are used to make the file system appear less complex. Data forks and resource forks are combined to appear as one single item in the file system. They have fallen out of favor because they are not directly compatible with non-Mac OS volumes, nor are they extensible.

Common file flags include the locked flag, which locks files from changes, and the hidden flag, which hides the item in the Finder. Common extended attributes used in the Finder are setting an item’s color label, stationary pad option, hide extension option, and Spotlight comments.

• Bundles and packages are used to combine complex items into individual folders. Packages have the additional advantage of appearing as a single item in the Finder. This allows software developers to combine resources into a single item and prevents
• users from messing with those resources.

Files are identified either by their file type attributes or their filename extension. Launch Services maintains a database of known applications and which file types they can open. When you double-click on a file in the Finder, Launch Services tries to find an appropriate match. You can override the default application selection in the Finder.

Three common UNIX commands that have been updated to support Mac file system metadata are cp, mv, and rm.

Zip archives are created with the Finder from a specific selection of items. Zip archives are compatible with many operating systems. On the other hand, disk images are created using Disk Utility and allow you to create highly flexible archive volumes that can contain nearly anything.

• The Spotlight search service creates index databases of file system metadata so that it
• can perform normally time-intensive searches nearly instantly.

Spotlight metadata index databases are stored at the root of every volume in a /.Spotlight-V100 folder. However, a FileVault user’s database is stored in his encrypted home folder. Also, the Mail application maintains its own database in each user’s home folder at ~/Library/Mail/Envelope Index. Spotlight plug-ins can be located in any Library in a folder named Spotlight.

Time Machine can back up to any Mac OS X Extended volume, including volumes from disk images stored on an AFP share from a Mac OS X or Mac OS X Server.

Time Machine starts with a full copy of the file system; then it records any changes to the file system and only copies the changes. It creates a simulation of the full file system using hard links for files that have not changed.

Though Spotlight indexes file and folder permissions, it will allow other users to search the contents of locally attached nonsystem volumes when ownership is ignored on those volumes.

Time Machine always ignores temporary files, Spotlight indexes, items in the Trash, and anything else that can be considered a cache. Time Machine will also ignore any files an application has defined as exempt, or any files you have defined as exempt in the Time Machine preferences.

Time Machine is inefficient at backing up large databases because it must back up the entire database file every time any change, no matter how small, is made to the database.

A previously backed-up item will not be available if your backup volume has become full and Time Machine has had to start deleting older items to make room for newer items.