Mac OS X version 10.7, called "Lion," was released in July 2011. It is no longer available from the Apple Store. The latest version of macOS is version 14.4.1, "Sonoma", relesed on 25 Mar 2024. There is no reason to run Lion instead of Mountain Lion.

See my Frequently Asked Questions about Lion.

New Features of Lion

(Claimed by Apple.)

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

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

Planning for the next version

Lion was followed by another version of OS X, "Mountain Lion," in late summer 2012. It was "inspired by iPad" and featured more game support, better security, and further iCloud integration. Keep a list of the software and devices you use and depend on.

Home | FAQ © 2010-2024, Tom Van Vleck updated 2024-03-27 10:03