Everything I know about the command line I learned from from Tron Legacy

Scene: In the Encom boardroom

Edward Dillenger, the evil wunderkind of Encom, on seeing the chaos of a barking dog video instead of the brand new Encom OS12:
ps -ef | grep -i os12

Thus he lists processes running that have a case insensitve match of the string os12.

Having found the rogue process above, Ed decides to terminate the puppy:

kill -9 17319

Scene: Sam, our hero, in his old man's underground laire

Finding a computer covered in dust, Sam wipes it (the dust) away and a lovely futuristic looking machine under a glass worktop comes to life:
whoami

He types, asking the machine for the effective username. It tells him: "flynn". Hmmm he thinks and then whips out a quick

uname -a

Oooh, gotta find out some operating system implementation info. The -a switch is a shortcut switch which basically means show all the info about the current OS. But this isn't enough for our hero. He has to try and log in, doesn't he:

login -n root

Now, he should have known better, I mean, his old man was the uber-geek genius of his generation. You can't just login as root without a password (yes I realise there is inconsistency in the story line here with the other terminal windows open etc but still). Next up, Sam tries the "backdoor"

backdoor

because every system in the world has a "backdoor" so named that will just let us in. On password change days, I kind of wish mine did.

Now, young Sam is curious. What was the old man up to?

bin/history

Hmm....nothing to see here, cows turn themselves inside out all the time, and dad clearly works on his last_will_and_testament.txt all the time too. Let's ignore all that and rather type in the ominous sounding LLLSDLaserControl command that was the last thing his dad typed in before disappearing off the face of the planet leaving his 'puter all powered up and such.

LLLSDLaserControl -ok 1

Well good thing he did too because he gets zapped into the grid and we get a movie out of the deal. Great Success!