How to prevent a mistaken rm -rf for specific folders?

Question

I think pretty much people here mistakenly 'rm -rf'ed the wrong directory, and hopefully it did not cause a huge damage.. Is there any way to prevent users from doing a similar unix horror story?? Someone mentioned (in the comments section of the previous link) that

... I am pretty sure now every unix course or company using unix sets rm -fr to disable accounts of people trying to run it or stop them from running it ...

Is there any implementation of that in any current Unix or Linux distro? And what is the common practice to prevent that error even from a sysadmin (with root access)?

It seems that there was some protection for the root directory (/) in Solaris (since 2005) and GNU (since 2006). Is there anyway to implement the same protection way to some other folders as well??

To give it more clarity, I was not asking about general advice about rm usage (and I've updated the title to indicate that more), I want something more like the root folder protection: in order to rm -rf / you have to pass a specific parameter: rm -rf --no-preserve-root /.. Is there similar implementations for customized set of directories? Or can I specify files in addition to / to be protected by the preserve-root option?

Answer 1

To avoid a mistaken rm -rf, do not type rm -rf.

If you need to delete a directory tree, I recommend the following workflow:

• If necessary, change to the parent of the directory you want to delete.
• mv directory-to-delete DELETE
• Explore DELETE and check that it is indeed what you wanted to delete
• rm -rf DELETE

Never call rm -rf with an argument other than DELETE. Doing the deletion in several stages gives you an opportunity to verify that you aren't deleting the wrong thing, either because of a typo (as in rm -rf /foo /bar instead of rm -rf /foo/bar) or because of a braino (oops, no, I meant to delete foo.old and keep foo.new).

If your problem is that you can't trust others not to type rm -rf, consider removing their admin privileges. There's a lot more that can go wrong than rm.

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Always make backups.

Periodically verify that your backups are working and up-to-date.

Keep everything that can't be easily downloaded from somewhere under version control.

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With a basic unix system, if you really want to make some directories undeletable by rm, replace (or better shadow) rm by a custom script that rejects certain arguments. Or by hg rm.

Some unix variants offer more possibilities.

• On OSX, you can set an access control list on a directory preventing deletion of the files and subdirectories inside it, without preventing the creation of new entries or modification of existing entries: chmod +a 'group:everyone deny delete_child' somedir (this doesn't prevent the deletion of files in subdirectories: if you want that, set the ACL on the subdirectory as well).
• On Linux, you can set rules in SELinux, AppArmor or other security frameworks that forbid rm to modify certain directories.

Answer 2

If you are using rm * and the zsh, you can set the option rmstarwait:

setopt rmstarwait

Now the shell warns when you're using the *:

> zsh -f
> setopt rmstarwait
> touch a b c
> rm *
zsh: sure you want to delete all the files in /home/unixuser [yn]? _

When you reject it (n), nothing happens. Otherwise all files will be deleted.

Answer 3

EDIT as suggested by comment:

You can change the attribute of to immutable the file or directory and then it cannot be deleted even by root until the attribute is removed.

chattr +i /some/important/file

This also means that the file cannot be written to or changed in anyway, even by root. Another attribute apparently available that I haven't used myself is the append attribute (chattr +a /some/important/file. Then the file can only be opened in append mode, meaning no deletion as well, but you can add to it (say a log file). This means you won't be able to edit it in vim for example, but you can do echo 'this adds a line' >> /some/important/file. Using > instead of >> will fail.

These attributes can be unset using a minus sign, i.e. chattr -i file

Otherwise, if this is not suitable, one thing I practice is to always ls /some/dir first, and then instead of retyping the command, press up arrow CTL-A, then delete the ls and type in my rm -rf if I need it. Not perfect, but by looking at the results of ls, you know before hand if it is what you wanted.

Answer 4

To protect against an accidental rm -rf * in a directory, create a file called "-i" (you can do this with emacs or some other program) in that directory. The shell will try to interpret -i and will cause it to go into interactive mode.

For example: You have a directory called rmtest with the file named -i inside. If you try to rm everything inside the directory, rm will first get -i passed to it and will go into interactive mode. If you put such a file inside the directories you would like to have some protection on, it might help.

Note that this is ineffective against rm -rf rmtest.

Answer 5

One possible choice is to stop using rm -rf and start using rm -ri. The extra i parameter there is to make sure that it asks if you are sure you want to delete the file.

Probably your best bet with it would be to alias rm -ri into something memorable like kill_it_with_fire. This way whenever you feel like removing something, go ahead and kill it with fire.

Answer 6

If you understand C programming language, I think it is possible to rewrite the rm source code and make a little patch for kernel. I saw this on one server and it was imposible to delete some important directoryes and when you type 'rm -rf /direcotyr' it send email to sysadmin.

Answer 7

I like to put the directory name first like this:

$ rm /directoryname -rf