#!/bin/bash
##################################################################
# Script: Zombie Slayer
# Author: Mitch Milner
# Date: 03/13/2013 ---> A good day to slay zombies
#
# Requirements: yum install gdb
# permissions to attach to the parent process
#
# This script works by using a debugger to
# attach to the parent process and then issuing
# a waitpid to the dead zombie. This will not kill
# the living parent process.
##################################################################

clear
# Wait for user input to proceed, give user a chance to cancel script
echo "***********************************************************"
echo -e "This script will terminate all zombie process."
echo -e "Press [ENTER] to continue or [CTRL] + C to cancel:"
echo "***********************************************************"
read cmd_string
echo -e "\n"

# initialize variables
intcount=0
lastparentid=0

# remove old gdb command file
rm -f /tmp/zombie_slayer.txt

# create the gdb command file
echo "***********************************************************"
echo "Creating command file..."
echo "***********************************************************"
ps -e -o ppid,pid,stat,command | grep Z | sort | while read LINE; do
intcount=$((intcount+1))
parentid=`echo $LINE | awk '{print $1}'`
zombieid=`echo $LINE | awk '{print $2}'`
verifyzombie=`echo $LINE | awk '{print $3}'`

# make sure this is a zombie file and we are not getting a Z from
# the command field of the ps -e -o ppid,pid,stat,command
if [ "$verifyzombie" == "Z" ]
then
if [ "$parentid" != "$lastparentid" ]
then
if [ "$lastparentid" != "0" ]
then
echo "detach" >> /tmp/zombie_slayer.txt
fi
echo "attach $parentid" >> /tmp/zombie_slayer.txt
fi
echo "call waitpid ($zombieid,0,0)" >> /tmp/zombie_slayer.txt
echo "Logging: Parent: $parentid Zombie: $zombieid"
lastparentid=$parentid
fi
done
if [ "$lastparentid" != "0" ]
then
echo "detach" >> /tmp/zombie_slayer.txt
fi

# Slay the zombies with gdb and the created command file
echo -e "\n\n"
echo "***********************************************************"
echo "Slaying zombie processes..."
echo "***********************************************************"
gdb -batch -x /tmp/zombie_slayer.txt
echo -e "\n\n"
echo "***********************************************************"
echo "Script complete."
echo "***********************************************************"
