"Thou shalt not kill"   (commandment six) (Exodus 20:13; Deuteronomy 5:17)

So simple, no exceptions, yet misinterpreted in the sense that strings are constantly being attached to it, such as (Is all killing the same? Is God's killing justified? What about when God orders Joshua to kill those canaanites, etc
.
“He that smites a man, so that he die, shall be surely put to death” (Ex. 21:12).

In short, my question is this, is there a "thou shalt not kill, "except, '"?
Think of cases like self-defense and the likes.

Before this discussion is begun, i'd like to point this out:

In John 14:15 Jesus says, “If you love me, keep my commandments.” and in John 15:10, “If you keep my commandments, you shall abide in my love; even as I have kept my Father's commandments, and abide in his love.” Jesus obeyed the Fathers Commandments and He asks us to demonstrate our love for Him by doing the same. We also find in 1 John 2:4, “He that saith, I know him, and keepeth not his commandments, is a liar, and the truth is not in him.”

Many Christians have been told that Jesus abolished the Ten Commandments. Here again Jesus gives us His own direct response, “Do not think that I have come to abolish the Law or the Prophets; I have not come to abolish them but to fulfil them. I tell you the truth, until heaven and earth disappear, not the smallest letter, not the least stroke of a pen, will by any means disappear from the Law until everything is accomplished. Anyone who breaks one of the least of these commandments and teaches others to do the same will be called least in the kingdom of heaven, but whoever practises and teaches these commands will be called great in the kingdom of heaven” Matthew 5:17-19. Again, Jesus speaks clearly and to the point. God’s law has not been abolished, and according to Christ’s own words, anyone who teaches so is directly contradicting Him and is in serious spiritual trouble.

http://www.gods-10-commandments.org/