Mac OS X version 10.7, called "Lion," was released in July 2011. More information on Lion is in the  Apple page on Lion and  Robert Mohns' review of Lion on MacInTouch. There is an extensive review by John Siracusa at  Ars Technica. Apple started shipping new Macintosh computers with Lion in July 2011. This note describes how to update a machine with an older version of MacOS to OS X 10.7 Lion. (I wrote notes last year on upgrading to OS X 10.6, "Snow Leopard.")

See Frequently Asked Questions about Lion.

New Features of Lion

(Claimed by Apple.)

• Optional simpler user interface, more like the iPad.
• Faster.
• Better security, including sandboxing, full disk encryption and encrypted backup.
• Better Time Machine backup.
• Updated applications will save automatically and resume where they left off.
• AirDrop wireless sharing between (some) Macs.
• Integration with iCloud.
•  "250 new features" according to Apple.

Should I Buy and Install Lion?

If your computer is working now, there is no need to change your OS.

Personally, I am waiting until some issues are resolved before upgrading my main Macs. Check  MacInTouch to see if there are problems that affect you.

Apple will probably drop support for OS X 10.5 (Leopard) eventually, since they usually support only two versions of the OS. Using an unsupported OS will still work, but if security problems are found in an unsupported version, Apple will not patch them.

Eventually, companies will write software that requires features of the latest Apple OS, and someday you will want to buy and use some of that software. Also, if your old Mac fails and you have to buy a new one, you'll end up migrating to Lion whether you were ready or not.

Show Stoppers

These are the issues I am waiting for information or fixes before installing Lion on my main Macs.

• John Nack and others report hangs when backing up to Time Machine.
• Quicken does not yet run on Lion: have to replace it, or wait for Intuit to produce its promised update in 2012.

What you Should Do Now to Get Ready for Lion

• Update to 10.6.8a (Snow Leopard) if you haven't done so already, and set up an App Store account.
• Use Software Update to keep all Apple software up to date.
• Apply all free updates to other software you use.
• Set up an external hard drive and use  Time Machine.
• If your computer has less than 2GB of memory, add more.
• Fix damaged and duplicate fonts.
• Use Disk Utility to repair permissions on your hard drive.

Who Can Update

Not everyone can use the new OS version.

• If you depend on the Classic environment to run Mac OS 9 programs, stick with OS X 10.4.
• If you have a Mac with a PowerPC processor, Lion won't work on it. Stick with OS X 10.5.8.
• First generation iMacs, MacBooks and MacBook Pros with the Core Duo or Core Solo processors cannot run Lion. Stick with OS X 10.6.8a.
• If you depend on PowerPC programs, the latest version you can run is Snow Leopard, since Lion will not support Rosetta, the PowerPC emulator. In particular, Microsoft Office 2004 and some features of Adobe CS3 will not run on Lion. (See  Adobe article.) Stick with OS X 10.6.8a.
  
  You could install VirtualBox (free) on your Mac, and install 10.6 into a virtual machine, and update it to 10.6.8a, and run your PowerPC programs under the emulated OS. I have not tried this.
• Some printers and scanners may not work. Those with PowerPC drivers will not work.
• The Apple USB Modem (discontinued in 2009) is not supported.
• Lion is only sold through the Mac App Store, which only runs on OS X 10.6.7 or later.
• You need at least 2GB of memory. Some users report that their machines with only 2GB are slower in Lion, and that even 4GB can be slow if you use many applications.
• Some Fink packages will not build, according to the  Fink site. In September 2011, a posting to the Fink Blog said, "We are currently creating a database showing which packages can be successfully installed under 10.7, and work is ongoing to add packages." This list has not been published yet, and the blog has not been updated since October 2011. Many packages have been updated: check the ones you use.
• There are reports of problems installing XS based CPAN Perl modules (such as crypto) in 10.7. It may be necessary to alter the Perl configuration to change compiler args. Google for the instructions, if you use such modules.

Plan your install

When you decide to install OS X 10.7, do it carefully. You may find that there are issues that affect you: do your homework.

The most important issue is that PowerPC-only programs are not supported. Users will have to buy new versions of their old software. You can find out which programs are affected by selecting  ► About This Mac ► More Info to start System Profiler, and then selecting Software ► Applications in the left sidebar. You can then sort on the "Kind" column and look for applications labeled "PowerPC." These are the ones that will have to be replaced. It looks to me like I will have to buy some new OCR software, since the OCR applications I got with my scanner are PowerPC only.

Make sure you back up your entire Snow Leopard disk before starting to install Lion.

Make a list of the hardware you depend on, and search the web to check that each device will work.

Leave yourself enough time. Upgrading will tie up your machine for a big part of a day. Installing takes an hour or two, but then your machine will want to re-do the Spotlight index and back up to Time Machine.

Particular issues before upgrading

• Programs that need paid upgrades: Microsoft Office 2004, Parallels <6.0, Suitcase Fusion <3, Cocktail, Photoshop CS3.
• Programs that need updates for Lion: Fink (see below), XCode (free from Apple), Little Snitch (free).
• Programs that will be upgraded later: Quicken 2007 (update expected in 2012). Wait to upgrade, or find an alternative.
• Programs that will not be upgraded: Some device drivers. The CUPS drivers may work for some printers.
• Programs that may cause problems with Lion on some MacBook Pro models: AirDisplay, iScreen.
• Features of previous releases no longer supported by Apple: Front Row; Time Machine to shared drive on Airport Extreme (though some say this still works).
• Fonts: damaged or duplicate fonts caused crashes in 10.6. Check your fonts with FontBook and fix them before upgrading.
• Peripherals. The Apple support forums are full of whining by people whose old printers no longer work. The printer manufacturers do not update every elderly printer driver for new operating systems, so some old printers won't work. It's not Apple's fault, but people are unhappy with Apple. Make sure your printers and scanners will be supported. Some manufacturers don't release updated drivers for their printers for months after a new Mac OS release.

Installing Lion

1. Clean up and update software before installing.
   • Purchase Lion in the Apple App Store. This will download a large file, the Lion Installer, to your disk. You can dig into this installer and burn a bootable Lion install DVD if you wish; Apple's license terms say you can update all your computers with one purchase.
   • Get the applications on your computer ready for 10.7: apply latest fixes. Remember that PowerPC programs will not work.
   • Delete junk files
   • Delete Safari, iTunes, and Firefox caches. I used Cocktail to clean all caches.
   • Empty trash.
   • Repair disk permissions with Disk Utility.
   • Clean up damaged and duplicate fonts.
   • If you modified your Apache configuration, save a copy of /etc/apache2/httpd.conf.
   • If you installed Perl modules via CPAN or Fink, make a list of them.
     perldoc perllocal | grep :: and
     fink list -i | grep -v virtual or dpkg --get-selections | cut -f1 > fink_packages.txt
2. Backup and prepare
   • If you use MySQL, backup the database with mysqldump databasename > db.sql
   • If you use Little Snitch, uninstall it.
   • BACK UP YOUR HARD DRIVE to an external disk. I used  SuperDuper to clone my whole drive.
3. Install
   • If you use a wireless mouse or keyboard, put in fresh batteries.
   • Set screen saver to NEVER, and turn off Time Machine.
   • Dismount and unplug or power off external drives.
   • (Some folks think you should boot from a Lion install disk at this point and run Disk Utility to repair the hard disk.)
   • Run the OS X 10.7 installer. It will run for about 15 minutes, then reboot, then run for about 45 minutes, then reboot again.
   • Select  ► Software Update to update to latest version, then run again to make sure all software is updated. (another hour or two)
   • Verify that the machine is working OK for you. If you have trouble, restore your backup and go back to the old version.
4. Recover
   • Wait for Spotlight to finish indexing (may take several hours). Performance will suck till it finishes.
   • Turn on screensaver and Time Machine. Time Machine may complain that it has to discard your old backup and start over, and then do a big backup, takes hours.
   • Repair permissions with Disk Utility again.
   • If you use Little Snitch, re-install and re-register it.
   • In Terminal, type the command java to trigger the installation of the Java runtime from the Internet.

Post Install Tasks

• Download the Apple Lion Recovery Disk Creator tool and burn a recovery disk for your machine, if you did not create a bootable Lion DVD.
• There are some Lion features I disable as soon as I install Lion:
  • Backwards scrolling. Select  ► System Preferences ► Mouse Preferences and uncheck the box at the top.
  • Finder status bar is hidden by default. Select View ► Show Status Bar to make it visible.
  • Hidden per-account ~/Library folder. In a Terminal window, do chflags nohidden ~/Library/ to make it visible.
  • Auto spellcheck correction. There are whole comical websites devoted to the idiocy of iPhone spelling corrections. I don't need this on my Mac. Select  ► System Preferences ► Languages ► Text and turn it off.
• Check that your printers work. If your printer will not work, you may be able to get it working by selecting  ► System Preferences ► Print&Scan, deleting the printer, and adding it again. You may have to use the open-source CUPS driver instead of the manufacturer's driver. (I have not tried this.)
• If you have a scanner, check that it works. If your scanner does not work, you may be able to get it working by purchasing and installing a third party scanner driver. Look into VueScan. (I have not tried this.)
• Install (free) Xcode 4.1 Developer Tools from Mac App Store. This takes a long time: it's a big download.
• Fink: see the Fink Project's  Lion instructions. Install Xcode 4.1 Developer Tools first. You must re-bootstrap Fink and rebuild the packages you use. This will take many hours.
• MySQL: Oracle has not yet provided a version of MySQL for OSX 10.7. I installed the Snow Leopard version 5.5.20 and reloaded my database. Things look OK. If you had MySQL running before upgrading to Lion, it might "just work." But back up your database before upgrading anyway, just in case. See my Snow Leopard MySQL instructions.
• Perl/CPAN: See the instructions for upgrading CPAN on Lion. Install Xcode 4.1 Developer Tools first.
• 64-bit upgrade: Have to do some extra work if you are upgrading from a 32-bit system to 64-bit. These changes are not urgent but will take advantage of the 64-bit architecture and should run more efficiently.
  • Eclipse 3.7: see my Eclipse instructions.
  • Change your shell environment to export VERSIONER_PERL_PREFER_32_BIT=no to avoid errors from dyld. (This was needed for Snow Leopard, not sure if still required.)
• Apache:
  • Apache is provided with OS X. Check that it is working. diff httpd.conf against your saved copy.
  • PHP may be turned off; turn it on and make sure it works.
• Security: Enable full disk encryption in  ► System Preferences ► Security. (This takes a while to finish, depending on how full your disk is.)
• Other
  • If you encounter Adobe licensing issues, follow  instructions in the Adobe forum. There is an "Adobe License Recovery" tool, but it is PowerPC only, which may cause problems. If you have to call Adobe help, they don't work weekends.

Lion observations

Installation went smoothly and the machine I upgraded seems to be working OK.

I have seen Bluetooth connections to keyboard and mouse fail at startup. Never saw this on Snow Leopard.

The photo screensaver can now pause, with the space bar, and go backwards and forwards with arrow keys.

Gotchas in Lion

• There were minor changes to the content of .vcf files exported by Address Book.
• There is an article in Ars Technica on gotchas with full disk encryption. Key point: "If you run the Lion Disk Recovery Assistant with FileVault 2 enabled, it creates recovery partitions that don't work." More detail at Mac OS X Hints. Making a bootable Lion Install DVD is definitely a good idea.
• QuickTime Player in Lion does not have all the functionality of previous versions. The trick is to preserve and use an earlier version of Quicktime. (Thanks Corby.)
• Lion locks files that use Auto Save and Versions if they have not been changed for 2 weeks, so that you have to unlock them before editing them. In System Preferences » Time Machine » Options, there is a control to set the length of time after the last edit before files are locked.

Planning for the next version

Lion will be followed by another version of OS X, "Mountain Lion," expected in late summer 2012. It will be "inspired by iPad" and will feature more game support, better security, and further iCloud integration. Here is another article about it. Keep a list of the software and devices you use and depend on.