How to forbid the execution of /bin/rm -f *?

Question

I cannot remember how many times I've listed a subdirectory and executed /bin/rm -f * in the current directory. Can anyone give suggestions to help me avoid this? What should I do if I want the system to warn me of the danger when I try to execute /bin/rm -f * ?

Answer 1

zsh by default asks you for confirmation, when you try and run any command called rm with * as a whole word on the command line (a feature inherited from tcsh though in tcsh it's not enabled by default).

$ rm -rf *
zsh: sure you want to delete all the files in / [yn]?

If you have to use bash, with recent versions of bash, you could do something approaching by using extdebug and the DEBUG trap:

shopt -s extdebug
check_for_rm_star() {
  case $1 in
    (rm*[\ /]"* "* | rm*[\ /]\*)
      read -p "check_for_rm_star: Are you sure? " -n1 answer < /dev/tty > /dev/tty
      echo > /dev/tty
      [[ $answer == [yY] ]]
  esac
}
trap 'check_for_rm_star "$BASH_COMMAND"' DEBUG

That's a simplistic one that would work for rm * and the most common cases but not for instance for rm "*" or /bin/rm * or : $(rm *), but you get the idea. Ideally, we'd need to parse $BASH_COMMAND the same was as the shell does to see if the first argument expands to rm or */rm, and to see if it's passed an unquoted *, but that can't really be done in a bulletproof fashion.

Answer 2

One possibility is to create a shell alias to map rm to a less destructive command. For instance:

alias rm='trash'  # from the package trash-cli

This does not delete the files, but places them in the trash bin, so you can restore them. However, this changes the semantics of the rm command (you can delete entire directories without -r, for example). Furthermore, it does not help if the full path is used.

Another possibility is to set up a regular backup, say once per hour. That way you can happily delete files and restore them later.

Answer 3

The only way to do that is to replace rm itself.

There is a wrapper script for rm that purports to provide a safe rm, which can be found at LaunchPad. From that page:

Safe-rm is a safety tool intended to prevent the accidental deletion of important files by replacing /bin/rm with a wrapper, which checks the given arguments against a configurable blacklist of files and directories that should never be removed.

The only issue I see with that is your example "dangerous" rm example is run with the full path, /bin/rm. So you couldn't put this wrapper script in a directory earlier in your $PATH, and let it get found when you run rm, and have the unwrapped "normal" rm available by typing the full path, /bin/rm, as you do above.

Answer 4

One simple solution is to add the alias rm="rm -i", then you will get asked before each removal if you are sure. But, as pointed out by one of my teachers, this might fool you that the unix system you are using is a safe and warm place, and that might be even more dangerous than accidentally running rm *