Apple Software Update: File Download Directory

Product: Apple OS X Lion 10.7

Following is the sample where Apple Software Update download new OS X 10.7.4 update package (extension pkg) to

1. While it is downloading

/private/var/folders/y2/nfm8z7vj2m9g96c401s88cfw0000gn/C/com.apple.SoftwareUpdate/content/downloads/34/15/041-5631/Zh54TkH3mLJkRTcRsJxXwM3J5GXFYBm8sr/MacOSXUpdCombo10.7.4.pkg

The long directory string will be different from system to system, but the common directory /private/var/folders will be identical for all OS

Use command below to find the exact directory:
$ find /private/var/folders -name "*.pkg" -type f 2> /dev/null

2. After downloaded

/Library/041-5631/MacOSXUpdCombo10.7.4.pkg

This is useful if you need to copy the pkg file to other OS X installation, or VMware OS instance