Long time Windows users know that if I told you to do this in a Command Prompt…
DELTREE /Y C:\WINDOWS
or
RD /S C:\WINDOWS
..this will wipe the entire C:\WINDOWS directory and cause the system to be inoperable within moments.
Seems some people in the Ubuntu forums are posting similar "dangerous commands" are doing the same thing, such as telling people to..
rm -rf /
rm -rf .
rm -rf *
..or similar. The above is more or less the equivalent of a DELTREE and/or RD in Windows. You run those commands and it’s bye-bye Ubuntu.
However what REALLY sucks is that there are lots of ways to screw up an Ubuntu (or any end user *nix) system.
Ordinarily you’d tell someone to RTFM if they didn’t know a Windows command – but you can’t do that for an Ubuntu system, because there’s no "M" in "RTFM".

Well, as far as i know all kind of Linux, which includes Ubuntu came with lots of manual, you just simply type “man command”, for example “man rm”. It will result a comprehensive manual, far more comprehensive than /? on Windows.
RE: “format c:” etc…
Right! Linux is no different except for those many more methods!
The key for ALL users is to really only pay attention to either Moderators or fanatical helpers (thank the Gods for them!) who have already posted hundreds of genuine replies.
Interestingly, the number of sickos that infest the world as child-molesters and black-hackers are about the same proportions. There aren’t many of them, but they can create havoc for the rest of us.
As a newbie to Lux (10 years been trying to get a working system to replace THAT other one, unsuccessfully) who tries new distros every year around this time AND who has been caught by both incompetent advice and deliberate morons having “fun” trashing peoples systems, when they aren’t smashing phone boxes and torturing cats ……..
Follow the advice above and never download any program that isn’t from a well-recognised source.
AND never forget to say thanks to those good people who do offer help so willingly and in simple good spirit AND save your diatribe for the actual developers – and remember to be nice to them too – they aren’t deliberately making things difficult. Remember THAT other one has had billions spent on it over many years and it is still a stuffup.
Peace! Or else!
AND have a nice pagan/Christian/whatever festive time.