safety script prevent accidental rm -rf

GATTACA · 10-23-2006, 10:33 PM

Hello.

I'm trying to prevent some students from accidentally deleting their important folders (they are new to the commandline).

What I would like would be something that warns you before executing a _specific_ command. For example, if the critical folder name is /home/student/homework. If the student were to type 'rm -rf /home/student/homework' the system would reply back with something like: "Are you sure you want to do this?(yes|no): "

BUT if the student types 'rm -rf /home/student/homework_old' the system won't object or ask questions.

Is this possible via a bash script?

Please let me know if this is unclear.
Thanks in advance.

paulsm4 · 10-23-2006, 10:48 PM

Sure. Here's one alternative:
http://are.berkeley.edu/mason/comput...s/unix/rm.html

The simplest, easiest approach is here:
http://tldp.org/LDP/abs/html/aliases.html

Just add the following to a user's local ~/.bashrc (or, better, to the global /etc/bashrc) file:

Code:

alias rm="rm -i"

'Hope that helps .. PSM

tuxdev · 10-23-2006, 10:56 PM

"rm -rf" actually won't object because that is the meaning of -f.
"rm -r" would complain if you have alias rm="rm -i". You could write

Code:

function rm {
   if [ $1 = "-r" ]; then
      /usr/bin/rm -f "$@"
   else
      /usr/bin/rm -i "$@"
   fi
}

My initial testing seems to indicate that the solution doesn't work, but that is probably because I'm doing something bad for the conditional.

sKaar · 10-27-2007, 04:57 PM

perhaps an option to list the files that will be deleted, with a default of don't proceed. i was reading the unix haters handbook and thought of all the times i had to make sure not to delete something important as root. i don't play with root much, so the likelihood i'll do something wrong is high.
the worst i did was formatting /home, but it was on reiserfs, so recovery was easy, everything at the root of /home was renamed, everything in the sub-directories was unmolested.

Disillusionist · 10-29-2007, 02:36 AM

Here is a sample shell front end to rm:

Code:

#!/bin/bash
###
### Shell front end for rm
###
case $# in
   0) echo "no file or directory passed to rm"
      exit 1;;

   1) ## 1 variable passed (should be a file)
      if [ -f $1 ]
      then
         /bin/rm $1
      else
         echo "File $1 not found"
         exit 2
      fi;;

   2) ## 2 variables check for -r -f -rf options
      l_force=`echo $1|sed 's/f//'`
      if [ "$l_force" != "$1" ]
      then
         # -f found!
         echo "Are you sure? Y/[N]"
         read l_ans
         case $l_ans in
            [Yy]|[Yy][Ee][Ss]) /bin/rm $1 $2;;
            *) exit 3;;
         esac
      else
         /bin/rm $1 $2
      fi;;
 
   *) echo "Syntax rm [options] [file(s) or directory]";;
esac

Save the file as new rm somewhere where everyone can access it eg: /usr/local/newrm

change permissions so everyone can execute it eg: chmod 755 /usr/local/newrm

add an alias for rm eg: alias rm='/usr/local/newrm'

Please note that I have not catered for the full option range supported by rm.

Feel free to modify the script in any way to better fit your needs.