No, this is a very old joke that uses the fact the command has “fr” in it to trick people about what the command does. Joking aside, here’s what the command actually does:

rm is the command to delete files and folders

-f is the force modifier. This means it’ll keep going even if it encounters problems and just delete as much as it can

-r is the recursive modifier. That means it’ll go down every folder it sees in the target and delete the contents as well, and delete the contents of folders of folders, etc.

/ is the target. This is the root of the filesystem. If you’re used to Windows, that’s like targeting C:.

Put it all together, and this command basically deletes your whole filesystem. A safeguard was put in place a while back due to people meming about this and causing newbies to delete their whole system. Now it won’t work unless you put in --no-preserve-root, which tells rm that yes, you really mean it, please delete my whole system.

/* as the target works around that safeguard, because technically deleting everything in root is not the same as deleting root itself.

And to avoid annoying error messages about preserving the root of the language, add a * at the end. Final command should look like this:

sudo rm -fr /*