Regardless of which operating you’re using, you’re bound to encounter applications that cause you problems. Some applications cause you problems so often that you eventually place a custom launcher or even a keyboard short-cut to a command that kills the applications. Firefox used to be one, but since version 3, it’s been much better. I still have problems, though now it’s always related to the Flash plug-in (which is rather troublesome in 64 bits mode). Another one that cause me problems regularly, is
EvilEvolution, the Exchange client for Linux.
One essential *nix command you should know, is kill. The kill command dispatches a signal to a process, by default, SIGTERM. This message instructs the process to terminate. It can ignore the signal, but in general, it will close gracefully after freeing resources. If the program ignores the signal or is in an unstable state, you can kill it “harder” by using kill -9, which sends the process an unmaskable SIGKILL. The process terminates instantly under most circumstances.