How can I open Java's Control Panel to change the security settings?
as of java9... (Oct 2017)
This assumes you have installed java9 yourself (since the webupd8 PPA method is currently broken). After repeated purging of all things java-related (especially the default-installed java), I've not taken the time to fix the "update alternatives" infrastructure, so that particular link to jcontrol is borked (that is, the answer above -- "just type jcontrol in a terminal window" -- does not work).
This also assumes you have a working java installation (java -version returns something).
# ls -al `which java`
You'll get something back like this:
lrwxrwxrwx ... /usr/bin/java -> /usr/java/default/bin/java
So your command will be:
Now, you can fix the alternatives link (the quick-and-dirty way), so you can just type jcontrol and have it work. I do recommend you use the update-alternatives structures (be sure you know what you are doing before taking these steps. I suggest using ls -al to check the links). This is done as root. You can put sudo in front of the commands if you feel better about doing that.
# ln -s -f /usr/java/default/bin/jcontrol /etc/alternatives/jcontrol # ln -s -f /etc/alternatives/jcontrol /usr/bin/jcontrol