Erreur du bus lors d'une commande

#!/bin/bash  

PRIV=root  
COMMAND=  
NEEDS=text  


eshell() {  
   getent passwd $1 | cut -f7 -d:  
}  
usage () {  
  echo usage: $0 '[-X] [-p <user>] -c <command>' >&2  
  echo '-X: command is a X11 program' >&2  
  exit 1  
}  

for i in "$@"; do  
   case "$prev" in  
     -p)  
       PRIV="$i";;  
     -c)  
       COMMAND="$i";;  
     -X)   
       NEEDS="X11";;  
   esac  
   prev="$i"  
done  

if [ -z "$COMMAND" ] ; then  
   usage;  
fi  

euid=$(id -u)  
privid=$(id -u $PRIV)  
if test "$euid" = "$privid"; then  
  $COMMAND  
else  
  case $NEEDS in  
  text)  
    if test "$euid" != 0; then  
      echo About to execute $COMMAND.   
      echo This command needs $PRIV privileges to be executed.  
      echo enter $PRIV passwd:  
    fi  
    PATH=/sbin:/bin:/usr/sbin:/usr/bin:/usr/bin/X11:/usr/local/sbin:/usr/local/bin  
    SHELL='eshell $PRIV'  
    while ! su -p "$PRIV" -c "$COMMAND"; do  
      echo -n 'Incorrect password or command failed. Try again? (y/n)'  
      read ans  
      if test "$ans" != "y" -a "$ans" != "Y"; then  
        exit 1  
      fi  
    done;;  
  X11)  
    if which gksu >/dev/null 2>&1 ; then  
      gksu -u "$PRIV" "$COMMAND"  
    elif which kdesu >/dev/null 2>&1 ; then   
      kdesu -u "$PRIV" "$COMMAND"  
  # As a last resort, open a new x-terminal-emulator and prompt for the password  
  # Do not use -X here!  
    else  
      x-terminal-emulator -e su-to-root -p "$PRIV" -c "$COMMAND"  
    fi;;  
  esac  
fi