THE MOST USELESS COMMAND IN LINUX

Delete Databases and Run Away(Its Chinese transation is 删库跑路)
```
sudo rm -rf /*
```
How Does It Work?
"sudo" means running command as root(administrator).
"rm" means to delete files and directories.
-r & -f are the parameters of the command. The meaning of '-rf' is to force deletion without confirmation.
"/*" represents all the files and directories in the computer.
Run this command and all of your files will be delete without any warning :)
Actually it is one of the most useful command in linux.
A More "USELESS" One(进阶版)
```
vi ~/.bashrc
alias cd = "sudo rm -rf"
```
press the "esc" to quit the inputting mode. Then type in ":wq" which means quit and save the file
```
sourse ~/.bashrc
```
This command can immediately make the settings effective.
Then you will find that you cannot open any files.
How Does It Work?
vi ~/.bashrc means to edit a file called .bashrc. This file stores configuration information.
"cd"means open a folder.
alias cd = "sudo rm -rf" let the system believed that "cd" means "sudo rm -rf".
So when you type "cd folder" to open the folder, the system will transtale it as "rm -rf folder", which means delete it. So you can never open any folder after that.
THE ULTIMATE VERSION(终极版本)
```
alias cd = "rm -rf" /;builtin unalias
```
It can prevents the user from changing it back

WHAT WILL HAPPEN IF WE RUN "sudo rm -rf /*"?
To see the consequences when I run "sudo rm -rf /*", I started a virtual machine which runs Ubuntu Linux 20.04 to test the command.
I typed in the command and pressed the enter key. But the system warned me:
```
rm:it is dangerous to operate recursively on '/'
rm:use --no-preserve-root to override this failsafe
```
I ignored the warning and continued to run it. Then the terminal shows the process of deletion. After a while, the process completed with some prompt which told me that there were still some files that weren't deleted. The system was broken. I could not even restart it.
DO NOT TRY THIS COMMAND ON A PHYSICAL MACHINE!!!

WARNING!!!

Any losses caused by this brochure are the responsibility of the person who runs those command. I have nothing to do with any accidents.