Backups

The install will wipe out and reset a few things, most notably for developers:

• /etc/apache2/httpd.conf (gets reset, not wiped)
• /etc/php.ini (gets wiped)

You may want to backup those two files before upgrading to ML.

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Installation

1. Install Mountain Lion from the Mac App Store
2. Install Xcode 4.4
3. Go to Xcode -> Preferences -> Downloads and install "Command Line Tools"

Homebrew and GCC

Apple doesn't include gcc4.2 with its command-line tools, need to grab that separately (I go through Homebrew, but you can download this directly from Apple I believe).

1. brew update
2. brew tap homebrew/dupes
3. brew install apple-gcc42

Note: I didn't export CC or anything else other than the brew install apple-gcc42.

Permissions

It appears that permissions get reset and /usr/local will be owned by root. To fix that:

• sudo chown -R `whoami` /usr/local

MySQL

If your MySQL databases disappear, don't worry, it's just permissions-related. You can fix that by updating your MySQL permissions/ownership:

• sudo chmod -R 755 /usr/local/mysql/data
• sudo chown -R mysql:mysql /usr/local/mysql/data

ImageMagick

Note: Be sure to have installed gcc-4.2 and the command-line tools from the steps above before doing this.

1. brew rm imagemagick
2. Install Xquartz (http://xquartz.macosforge.org/downloads/SL/XQuartz-2.7.2.dmg)
3. brew install imagemagick
4. gem uninstall rmagick
5. gem install rmagick

(for bundled rmagick, see below)

Bundler

For Rails apps, I suggest removing ~/.bundle completely so gems get reinstalled and recompiled properly.

• rm -fr ~/.bundle

Apache

Some are having difficulty with Apache not auto-starting after the install. Here's how to fix that:

• sudo launchctl load -w /System/Library/LaunchDaemons/org.apache.httpd.plist

The -w makes it permanent. It will be reloaded when you reboot.