The value of the screen saver settings for the current user (at least 10.6.x up) stored in the properties list file in ~/Library/Preferences/com.apple.screensaver.plist. Perhaps there is no value if the user decided to turn off automatic screen blanking / saving.
You can read the value using a command line utility called defaults (1) :
defaults read com.apple.screensaver idleTime
defaults -currentHost read com.apple.screensaver idleTime
The former provides access to the settings of the current user, the latter to system defaults, if one exists.
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Apple Xcode / .