Preventing deletion of system/shell aliased folders

Question

Is there a way to prevent deletion of system/shell aliased folders? I want these commands to fail. My shell is bash.

Such as:

$rm -rf .
$rm -rf ..
$rm -rf ~
$rm -rf *

Answer 1

Note that ~ and * are expanded by the shell before passing the arguments to rm.

The only way to do it is to define a function named rm that parses the arguments before invoking command rm ...

I would not recommend it. When you get lazy, you get in trouble when you sit at some other computer without your self-protections. I used to alias rm="rm -i" before that bit me.

Answer 2

Not sure if there is an answer to this, but one thing I do in my .bashrc is to set GLOBIGNORE=.:.., this stops glob expansions from matching . and ... It also effectively enables dotglob which might not be what you want (GLOBIGNORE=.:..:.* stops this). I find this useful for me.

Answer 3

With recent versions of bash:

typetext() {
  perl -le 'require "sys/ioctl.ph";
    ioctl(STDIN, &TIOCSTI, $_) for split "", join " ", @ARGV' "$@"
}
checkrm() {
  local re='\<rm\>.*[[:blank:]]([.*~]|\.\.)([[:blank:]]|$)'
  if [[ $READLINE_LINE =~ $re ]]; then
    printf > /dev/tty "Are you sure? "
    read -n1 k
    echo
    if [[ $k != [yY] ]]; then
      READLINE_LINE=
      return
    fi
  fi
  typetext $'\n'
}  <> /dev/tty >&0
bind -x '"\C-m": checkrm'

Basically, upon pressing Return, our checkrm function is invoked.

It looks in the currently entered command line ($READLINE_LINE for which you need bash 4.3 or newer) for a rm word (also matches /bin/rm, but not in rmdir) followed by a *, ., ~ or .. argument.

If it matches, it prompts the user for confirmation. If confirmed, a newline character is inserted in tty input buffer for the command to be accepted (both CR and LF are bound to accept line, we're only wrapping CR); if not, the current buffer is emptied.

Note that with versions of bash prior to 4.4, there was a hitting a bug that caused readline to stop functioning properly when a job was suspended.