Tips on downgrading applications

Recently, after swapping a couple of machines (I sent my first-generation Intel-based Mac mini back to the Macworld offices, and we bought an iMac for the kids and general use), I realized that I had inadvertently also disabled my locally-hosted Web sites: I used to use the mini as a local Web server, and it served out copies of the Mac OS X Hints site, as well as the various family sites I maintain. I didn't really want to keep the iMac running all the time just to have the Web server running, so I decided to move the server to my Mac Pro.

While OS X ships with a built-in Web server, it doesn't ship with MySQL, the database engine that enables sites such as macosxhints.com to work. Installing it is relatively straightforward--there are OS X installer versions available on the MySQL site. About the only trick comes in choosing which version of MySQL to install--some content management systems only work with certain versions. In my case, I wanted MySQL 4.1 for compatibility with the macosxhints.com site. Unfortunately, I managed to download and install version 5.0 without noticing. As soon as I noticed the problem, I downloaded the 4.1 package, and attempted to install it. The installer, however, refused to proceed, telling me there was already a newer version of MySQL installed.

Since the installer didn't want to install due to the presence of the newer version of MySQL, I thought I'd first get rid of that newer version. In the case of MySQL, all the code lives in the /usr/local/mysql directory, which is actually a symbolic link (like an alias in the Finder) to a directory with a much longer name. So in Terminal, I issued a sudo rm -r /usr/local/mysql-long-directory-name to remove all the MySQL code. Note that this command will delete all of your MySQL databases in addition to MySQL itself! In my case, I didn't care, because I hadn't yet migrated the databases over to the Mac Pro.

I then tried to run the installer again, but it still failed, saying a newer version was installed. After some thinking, I remembered the /Library/Receipts folder--this is where installers write out records of what they did. Perhaps, I thought, the MySQL installer is looking at the Receipts folder, seeing the MySQL 5.0 receipt, and using that as the basis for stopping the install.

In Terminal, I did cd /Library/Receipts, and then ls -d mysql* to see what was there. Sure enough, I found a receipt for the MySQL 5 installation, named something like mysql-standard-5.0.67-apple-darwin8.5.1-i686.pkg. I deleted that directory (sudo rm -r mysql-standard...), and then ran the 4.1 installer again. Success! The 4.1 install ran fine, I then moved over my databases, and had the internal web server up and running again a few minutes later. OK, so it was several hours later; it just seemed like a few minutes!

Generalizing from my experiences with MySQL, here's the process I would follow to downgrade a program that was installed with Apple's installer:

1.

Sign up for ITworld's Daily newsletter
Follow ITworld on Twitter @IT_world

• Email
• Print
• Share
  • Slashdot
  • Digg
  • Stumble
  • Reddit
  • Newsvine