Behind the scenes, all of your photos sit in an extremely important folder called the iPhoto Library folder. Understanding this fact is the first step to mastering a useful bunch of hints.
Given its druthers, iPhoto would store its iPhoto Library folder in your Home → Pictures folder. But what if you want to keep your photos somewhere else, such as an external drive (so that you can easily move your photos from one Mac to another), or on a second, larger hard drive?
Unlike iTunes, which lets you choose any folder you like for storing your music, iPhoto doesn’t have a similar preference setting. Still, you can do the deed using either iPhoto Library Manager (see the next hint) or Terminal.
Make sure iPhoto isn’t running, then open Terminal (Section P.3.5.3). At the prompt, type:
defaults write com.apple.iPhoto RootDirectory
The only part of the command you need to change is the /path/to/new/home part, which specifies the new iPhoto Library location.
For example, if you wanted to park the library on a hard drive named Room to Grow in a folder named My Images, then "/path/to/new/home" would become "/Volumes/Room to Grow/My Images“. (Quotes are required in Unix if the folder or file names contain spaces; you also have to add "/Volumes" whenever you specify any location that isn’t on your main, startup hard drive.)
See Section P.3.5.4 for details on the defaults write command.
Once you press Enter and exit Terminal, iPhoto creates and manages ...