On Thu, 2005-01-20 at 04:43, vijay mishra wrote:
HI THIS IS VIJAY CAN ANY BODY HELP BY TELLING THAT HOW DOES ZOMBIE WORK, AND WHAT IS DDOS ( DISTRIBUTED DENIAL OF SERVICE ) .
Hi Vijay,
Here is some information that I can give about the zombie process.
When Parent process calls fork() system call child process is created. actually it is exact copy of the parent process but with new Process ID.
Exit status of the child process is passed to parent through wait() system call. If child is terminated before parent calling wait() then exit status would be lost.and parent would not know whether the child is exited normally or not. and therefore new process state called zombie state is introduced.
If such condition occurs then child process enters in zombie state till parent calls wait(). Once parent calls wait() , termination status is passed to it and parent cleans up the child.
Zombie State : The state in which process is terminated but not cleaned up.
if parent is at wait() call and child is still running then parent has to wait till child completes its execution.
if parent is not calling wait()then ?????
Does child process remains in zombie state ??????????...............
No becauess in Linux there is special process init which is parent of all process. These zombies then becomes child of init.
This init process routinely executes wait() whose side effect is to get rid of all zombies.
there are variants of wait() system call.
for more information search on Google. .......... No other way.
-Sachin
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