Most of the time, none of us willingly performs an action that will literally break our operating systems and force us to reinstall them. But what if such an action could easily occur even by accident on the user’s part? Today’s SuperUser Q&A post has the answer to a confused reader’s question.

Today’s Question & Answer session comes to us courtesy of SuperUser—a subdivision of Stack Exchange, a community-driven grouping of Q&A web sites.

The Question

SuperUser reader fangxing wants to know why Linux would allow users to remove the root directory:

When I installed Linux on my computer for the first time, I always liked to use root because I did not need to add sudo and enter my password every time I executed a command that needed root level permissions.

One day, I just wanted to remove a directory and ran rm -rf  /, which “broke” my system. I have been wondering why Linux’s designers did not block such a dangerous command from being run so easily.

Why does Linux allow users to remove the root directory?

The Answer

SuperUser contributor Ben N has the answer for us:

Why should it block you from doing whatever you want with your own computer? Logging in as root or using sudo is literally saying to the machine, “I know what I am doing.” Preventing people from doing dubious things usually also prevents them from doing clever things (as expressed by Raymond Chen).

Besides, there is one singularly good reason to allow a user to torch the root directory: decommissioning a computer by completely erasing the operating system and file system. (Danger! On some UEFI systems, rm -rf / can brick the physical machine too.) It is also a reasonable thing to do inside a chroot jail.

Apparently, people accidentally ran the command so much that a safety feature was added. rm -rf / does nothing on most systems unless –no-preserve-root is also supplied, and there is no way that you can type that by accident. That also helps guard against poorly-written but well-intentioned shell scripts.

Have something to add to the explanation? Sound off in the comments. Want to read more answers from other tech-savvy Stack Exchange users? Check out the full discussion thread here.

Image Credit: Wikimedia Commons

Akemi Iwaya
Akemi Iwaya has been part of the How-To Geek/LifeSavvy Media team since 2009. She has previously written under the pen name "Asian Angel" and was a Lifehacker intern before joining How-To Geek/LifeSavvy Media. She has been quoted as an authoritative source by ZDNet Worldwide.
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