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Does this really work? Wouldn't
rmremove itself in/binearly in the process?I think it would continue even after it's own deletion as the binary is already loaded into memory, so process is not dependent on the file system. Still doubt that it'll complete successfully. Most likely the system crashes in the middle.
I thought - - no-preserve root also needed to be added as an argument for self destruct to completely work.
Yes, though you could also do
rm -rf /*afaik to not need--no-preserve-rooti dont get why you can't just do
sudo rm -fr /because it won't let you do that:
elvith@testvm:~$ sudo rm -fr /
rm: it is dangerous to operate recursively on '/'
rm: use --no-preserve-root to override this failsafe
as the binary is already loaded into memory
That’s not the reason why it continues. It’s because there’s still a file descriptor open to
rm.
In Unix/Linux, a removed file only disappears when the last file descriptor to it is gone. As long as the file
/usr/bin/rmis still opened by a process (and it is, because it is running) it will not actually be deleted from disk from the perspective of that process.This also why removing a log file that's actively being written to doesn't clear up filesystem space, and why it's more effective to truncate it instead. ( e.g. Run
> /var/log/myhugeactivelogfile.loginstead ofrm /var/log/myhugeactivelogfile.log)Sometimes you can even use this to recover an accidentally deleted file, if it's still held open in a process. You can go to
/proc/$PID/fd, where$PIDis the process ID of the process holding the file open, and find all the file descriptors it has in use, and then copy the lost content from there.rm doesn't remove memory in RAM
That’s not the reason why it continues. It’s because there’s still a file descriptor open to
rm.
Since you forgot to add - - preserve-root It won't go too far. But at some point the system wants to load a file that is deleted and the kernel will panic. System crash. Delete incomplete. But rest assured, the important stuff is gone.
Since you forgot to add - - preserve-root It won’t go too far
Go on then ... try it.
Or don't because you will erase your system. (Hint: it's in the asterisk)
Or was it non preserve. I never tried it though. I guess a vm should be fine to test it. On the other hand I don't care enough.
The flag is called
--no-preserve-root, but the flag wouldn't do anything here because you're not deleting root (/), you're deleting all non-hidden files and directories under root (/*), and rm will just let you do it.Pretty sure it's --no-preserve-root or something similar.
rm doesn't remove things from memory, and binaries as small as rm can typically be entirely loaded into memory while running. Programs typically only run from memory, not the disk directly.