The 5 New Linux-Destroying Spells

This is Saito from the infrastructure team

This time, I'd like to change things up and introduce the most dangerous Linux commands in a ranking format. The title is "The New 5 Great Spells of Destruction."

We also have some items that are not on the ranking list.
Let's get started.

5th place: iptables

sudo iptables -I INPUT -j DROP

● Evaluation point: It stops working in an instant

iptables is troublesome to use normally, but this command stops working the moment you type it

Therefore, it would be very troublesome if you try this on a server that cannot be restarted. On the other hand, if you can just restart it, it will still be possible to fix the problem

4th place: git

git reset --hard HEAD~3 && git push -u --force origin master

● Evaluation point: It will cause trouble for your colleagues

Forces an overwrite of the remote repository

Doing this will delete all of your coworkers' pushes, which is even worse since you're resetting them. This is something you should never do if you're working with a group of remote repositories

3rd place: chmod

sudo chmod -R 000 /

● Evaluation points: All become zero

It's a pretty dangerous command, but it goes through quite easily

After the command passes without any issues, you lose all access to the server, but the pwd command still returns the correct result

2nd place: rsync

mkdir hoge;sudo rsync -av --delete-excluded /hoge/ /

● Evaluation point: No longer synchronized

rsync is a command for synchronizing files, and it has many options. Of the many options, many of the necessary ones are grouped together under -a

So don't be afraid to use options with the word "delete" in the title.
The above command will erase everything by syncing an empty file with your OS.

1st place:rm

sudo rm -rf / --no-preserve-root

● Evaluation point: It can be erased after all

On recent OSes, if you type the command rm -rf /, which deletes everything under /, the OS will pause and the command will not run

However, there is an option that will nullify this kindness: --no-preserve-root . With this, everything will disappear.

Not ranked

rm -rf <folder>

● Evaluation point: Easy to use

Using sudo makes this a very dangerous command, because it makes it very easy to delete folders and files. (Actually, there is a way to restore them, but we'll talk about that another time.)

This is a command that amateurs cannot type casually. I think some people may use it depending on the situation, so I have not ranked it. Please leave this type of work to server engineers as much as possible

summary

What did you think?

If you're in the same industry, your heart rate may have increased. Have a cup of tea and relax

There are also several other dangerous commands, such as the fork bomb :(){ :|:& };:, so please do not try fork bombs on Docker. There are precedents where they have caused fatal damage to the host OS

All the commands introduced here were performed on VirtualBox + Vagrant, but the entire box may disappear, or the Vagrantfile permissions or file itself may be lost. Please do not use this on a business computer

That's all