How can I enable java applet plug-in and Web Start applications via terminal?

Question

Since the last Java update to Snow Leopard, I have found that the system periodically disables the Java applet plug-in after a period of disuse.  I know I can go to /Applications/Utilities/Java Preferences and just click to re-enable Java.  But I want to write a script which will do this periodically for a couple hundred Mac users where I work. 
My question is - how can I reenable the Java applet plug-in and web start applications via Terminal command?  Is this possible?  Is there a plist file that can be modified, etc.?
Bob Reed

Answer 1

It is my understanding that Apple's most recent Java update automatically disables Java after a certain period of time that it hasn't been used.  We don't want users to have to keep re-enabling it.  So we wanted to find a way to do this via script either run by a Casper JSS server or stored locally on each workstation.   With the guidance provided by Mark Jalbert above and some text from a script written by Rich Trouton, I was able to make a script (with some minor changes) and a launch agent to re-run the script upon login.  So the preference is always enabled.
For your reference, the script content is:
#!/bin/sh
# DYNAMICALLY SET THE UUID FOR THE BYHOST FILE NAMING
if [[ `ioreg -rd1 -c IOPlatformExpertDevice | grep -i "UUID" | cut -c27-50` == "00000000-0000-1000-8000-" ]]; then
MAC_UUID=`ioreg -rd1 -c IOPlatformExpertDevice | grep -i "UUID" | cut -c51-62 | awk {'print tolower()'}`
elif [[ `ioreg -rd1 -c IOPlatformExpertDevice | grep -i "UUID" | cut -c27-50` != "00000000-0000-1000-8000-" ]]; then
MAC_UUID=`ioreg -rd1 -c IOPlatformExpertDevice | grep -i "UUID" | cut -c27-62`
fi
# Set the the "Enable applet plug-in and Web Start Applications" setting in the Java Preferences for the current user.
/usr/libexec/PlistBuddy -c "Delete :GeneralByTask:Any:WebComponentsEnabled" /Users/$USER/Library/Preferences/ByHost/com.apple.java.JavaPreferences.${MAC_UU ID}.plist
/usr/libexec/PlistBuddy -c "Add :GeneralByTask:Any:WebComponentsEnabled bool true" /Users/$USER/Library/Preferences/ByHost/com.apple.java.JavaPreferences.${MAC_UU ID}.plist
/usr/libexec/PlistBuddy -c "Delete :GeneralByTask:Any:WebComponentsLastUsed" /Users/$USER/Library/Preferences/ByHost/com.apple.java.JavaPreferences.${MAC_UU ID}.plist
/usr/libexec/PlistBuddy -c "Add :GeneralByTask:Any:WebComponentsLastUsed real $(( $(date "+%s") - 978307200 ))" /Users/$USER/Library/Preferences/ByHost/com.apple.java.JavaPreferences.${MAC_UU ID}.plist
The launch agent plist content is:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
          <key>Disabled</key>
          <false/>
          <key>Label</key>
          <string>org.XXXXX.enableJavaPlugin</string>
          <key>ProgramArguments</key>
          <array>
                    <string>sh</string>
                    <string>/Library/Scripts/XXXXX/enableJava_plugin.sh</string>
          </array>
          <key>RunAtLoad</key>
          <true/>
          <key>StartOnMount</key>
          <true/>
</dict>
</plist>
I hope this is helpful to anyone wishing to keep the Java web plugin enabled.
Bob
Message was edited by: Robert Reed2