- In This Chapter
- What You Need to Install and Run Mac OS X
- Installing or Reinstalling Mac OS X
- Restoring Mac OS Software
- What About Mac OS 9?
- Selectively Installing Mac OS X Files
- Upgrading Mac OS X
- Updating Mac OS X
- Downgrading and Re-upgrading Mac OS X
- Uninstalling Mac OS X
- Understanding Image, Installer Package, and Receipt Files
- Backing Up and Restoring Mac OS X Volumes
- Creating an Emergency Startup Volume
- Troubleshooting Tips and Hints: Installing Software
Updating Mac OS X
Once you have installed and (if necessary) initially updated to the latest version of Mac OS X, you will want to keep it up to date. Apple regularly releases software updates (as opposed to upgrades, as covered in the previous section) and makes them available via both the Software Update System Preferences pane and the Apple Web site. Because Software Update is the simplest and fastest way to stay current, I recommend using it. I gave a brief overview of how to use Software Update in Chapter 2; the following provides some additional details.
Apple releases three categories of updates, almost all of which are available via Software Update:
- General updates to Mac OS X. These are the Combo, Delta, and Patch updates, as described previously in "Cautions regarding extracting files from update packages."Note: In no case do these updates contain the complete set of software you need to run Mac OS X. For this, you need a Mac OS X Install disc.
- Security updates to Mac OS X. These updates, with names like Security Update 2005-05, modify the OS to plug various security leaks, but do not alter the version number of the OS.
- Separate updates to specific components of Mac OS X as well as to software not included as part of Mac OS X. For example, you may see a QuickTime update, an iPhoto update, or a Pages update.
Although I generally recommend installing updates—Apple provides them to fix bugs and to add new features—I also recommend waiting a few days after an update has been released to do so. Use this time to check the Web (for example, the MacFixIt site) to make sure the software doesn't contain any significant bugs that weren't discovered until after its release. And always make backups of critical files before installing an update.
How and why things can go wrong
After installing software, it's possible to start getting permissions errors when trying to launch various applications, including applications unrelated to the one(s) you just installed. In extreme cases, the system may even become unusable. How can this happen simply as a result of running the Installer utility? The answer is two-pronged: When installing software, you're typically asked to enter your administrative password, which gives the Installer temporary root access. In addition, script files within an Install .pkg that are run as part of the installation can contain instructions to modify permissions of files and folders—or even to delete certain files. These script files, typically located in the Resources folder inside the package file, have names like "preflight," "postflight," and "postinstall." If these scripts contain errors that cause permission changes or file deletions that should not occur, you can wind up with serious problems.
Basically, you just have to trust that the software developer has not made such an error. And usually your trust is well placed—such mistakes are rare. Although the risk rises slightly with software that does not come from Apple, even Apple can make a mistake here.
Here's one example: When Apple initially released iTunes 2.0 as a free upgrade on the Web, it was supposed to delete any older version of iTunes found on your drive before installing the new version. Unfortunately, the installer .pkg file contained a nasty quirk: Due to an error in how it was set up to work, the installation sometimes failed to install iTunes at all. Even worse, when attempting to remove an older version of iTunes, the installer sometimes also removed much of the data on your drive! This horrendous bug was fixed the same day via another iTunes update—but not before hundreds of users lost files.
In general, if an installer causes a serious mistake, you will need to reinstall Mac OS X to fix it—and then restore any lost files from your backups.
Updating from Software Update
The simplest way to check for and install updates is to select Software Update from the System Preferences window, the Apple menu, or the About This Mac window.
Software Update System Preferences pane
As discussed in Chapter 2, the Software Update System Preferences pane includes two tabs, each of which accesses a separate pane:
Update Software. In this pane, you can choose the "Check for updates" option—at daily, weekly, or monthly intervals. With this option selected, you can also choose the option to "Download important updates in the background." With this selected, updates that Apple deems important will be downloaded without the system's first asking your permission (though you will still be asked for confirmation before the software is installed).
Alternatively, you can manually check for updates at any time by clicking the Check Now button.
If you click Check Now and there are no new updates, a message will appear telling you that you are currently up to date. Otherwise, you will have the option to install new uninstalled software, as described in "Software Update application," below.
- Installed Updates. This pane presents you with a list of everything you've installed via Software Update (though the contents may get wiped out each time you upgrade to a new version of Mac OS X). Alternatively, you can view this listing from a log file by using the Open as Log File button.
Figure 3.14 The Software Update System Preferences pane.
Software Update application
A separate application, also called Software Update (located in /System/Library/CoreServices), is launched after any of the following have occurred: You clicked Check Now in the Software Update System Preferences pane; an automatic check was initiated (assuming new software is available); or you clicked Software Update in the About This Mac window. The Software Update window displays a list of all available updates. Note, however, that it lists only Mac OS X and application software from Apple and occasional third-party software (such as StuffIt Expander) that is included with Mac OS X.
Figure 3.15 The Software Update application: The main window shows a needed update—select it and click the Install 1 Item button to install it.
Figure 3.16 Software Update's Update menu.
To install the software listed in the Software Update application, you simply check the box(es) in the Install column for each item you want to install. Then click the Install Item(s) button. Alternatively, after selecting the items to install, you can go to the Update menu and select one of the following four commands:
Download Only. This downloads the update file (typically a .pkg file, referred to as a stand-alone update) to a folder named Packages, located in the root-level Library folder. The folder is automatically opened in the Finder when the download is complete. You must then manually open the .pkg file (which launches the Installer application) when you're ready to install it.
This option is useful if you want to retain a copy of the .pkg file after installing the software. One reason to do this would be so that you can reinstall the update later (should you erase your drive, for example) without having to redownload it. Another reason would be to install the update on multiple machines without having to download the update from the Internet each time. Also, if the update provides any Custom Install options, running the Installer manually is the only way to access them.
If you use this option but do not install the software, Software Update will not "remember" that you downloaded the file. Instead, Software Update will continue to list the downloaded file as an uninstalled update until you actually install it. In fact, if you subsequently select the Install command, it will redownload the update, rather than using the copy you previously downloaded.
Install. This is just like clicking the Install Item(s) button: It both downloads and installs the selected update(s). Onscreen messages inform you of Software Update's progress, from downloading to installing.
The downloaded .pkg file(s) are kept hidden in the Finder. They are automatically deleted the next time you restart—making it difficult to save them for future use.
The Install option is especially convenient for installing multiple items that require restarting the Mac. With the Download Only option, you would have to run each update separately (although you can have them all open in the Installer utility at one time). With Software Update, all updates are installed before any restart is requested. The Software Update option is also the simplest because it requires no further action on the part of the user.
If you select this option and it stalls while installing the software (after having downloaded it), force-quit Software Update. Next time, select Download Only and manually install the software. This often works around the problem.
- Install and Keep Package. This option combines the previous two options: It automatically installs the software, plus it saves a copy of the update package in the Packages folder. This is the option I typically choose.
- Ignore Update. If you select this option, the update is removed from the list. You will not be notified again of this update or of any subsequent updates for the same software. You may end up choosing this option for software you don't need (such as an iPod update if you don't own an iPod). Should you change your mind and want to get the update later, you can select Reset Ignored Updates from the Software Update menu.If you don't choose to ignore an update but don't go ahead and install it either, this same software update will be listed again the next time you check for updates.
If an update requires administrator approval, you will be asked for your admin-level user name and password before the update will install.
If an update requires that you restart your Mac, a restart symbol will appear to the left of the update name.
Some updates appear only in Software Update if certain prior updates have been installed. For example, Apple at one point released an update to the Installer application itself. No newer updates would appear in Software Update until after the new Installer had been installed. For this reason, once you've installed an update, return to the Software Update System Preferences Pane and click Update Now again. Keep doing this until no new updates appear. Actually, you should no longer have to do this in Panther or later, because Software Update does this rechecking automatically until no new updates appear.
After reinstalling Mac OS X via an Archive and Install, Software Update may not list the more recent updates because it erroneously believes they are already installed. Thus, as a safeguard, check Apple's Web site for recent updates regardless of what Software Update says.
Note: In Jaguar or later, you can no longer update Mac OS 9 by running Software Update via Classic.
Updating from the Installer package (.pkg) file
You can install a software update by first downloading the .pkg file from the Web (such as from Apple's Web site at www.info.apple.com/downloads or via the Download Only option in Software Update). These stand-alone updates open in the Installer utility and proceed in a manner similar to how Mac OS X itself was installed from the Install CDs or DVD. The main difference is that you don't need to boot from a Mac OS X Install CD (or any other CD) to install these updates. You can do so while running Mac OS X, directly from your drive. You will be asked to enter your administrative password before you are allowed to perform the installation.
Recall that you can use the Show Files command, in the Installer, to view and save a list of all files that the update will install.
This method is essentially the same as using Software Update and selecting the Download Only option; however, there are three differences of note:
- Downloaded update files typically download as .dmg files. The actual .pkg file is on the mounted .dmg image.
- Occasionally, updates (even those from Apple) are available only via Web download, with no Software Update option.
- A potential advantage of using Software Update to download the file is that it often lists the latest updates even sooner than Apple's Web site.
- Software Update will always download the smallest version of the update; for example, if Software Update determines that you only need the Patch version, you can't download the Delta version or the Combo version. Some people prefer to always use a Combo version of the update; to do so, you need to download the update from Apple's Web site.
Skip the restart?
After you've completed your software installation, either via the Installer or Software Update, some installations will insist that you restart your Mac before continuing. You should follow this advice, especially if you intend to use the installed software immediately. However, on occasions in which it's not convenient to restart immediately (say, because you want to finish work or save documents in another application), you can simply switch to a different application and finish up. When you're ready, return to the Installer application and click Restart.
Alternatively, you may want to install a second or third program before restarting, so you don't have to restart each time. With Software Update, this is not an issue; it does all selected installations before requesting that you restart. If, instead, you are using the Installer application, you can accomplish the same goal by launching all desired Installer .pkg files without quitting the Installer application. This works because, starting in Panther, the Installer can have multiple packages open at the same time. However, you cannot actively install more than one at time; you must do each install sequentially (waiting until the optimization stage is completed for each one)—just don't click the Restart button for any installation until all are finished. This allows you to install multiple packages before restarting.
Alternatively, you can quit by choosing Quit (or, if needed, Option-Quit) from the Dock menu of the Installer or Software Update applications. Any of these options bypass the Restart request.