about process

[Eris]

On Friday 12 August 2005 12:08 am, peeyush kr wrote:
> Hi friends,
>
> I want to know about the process that run in the background.
> there are three processes  1.active  2.sleep  3. zombi

When a process is active then it is actually executing on the CPU.  An active 
process has it's program code loaded into RAM.

When a process is sleeping, then it is not executing.  Instead it is waiting 
for something to happen.  It may be waiting for the disk controller to read 
data off of the hard disk, or it may be waiting for data to arrive on the 
ethernet port.  A process can sleep for many different reasons.  A process 
that is sleeping may have it's code and data moved out of RAM and onto the 
swap partition if it has been waiting long enough.

A zombie process is one that has already terminated and been unloaded from 
RAM, so it isn't using your memory.  But it is still listed in the process 
list because no one has checked its return value yet.  (The return value is 
stored in the process table entry, so that entry has to be kept around until 
the return value is checked, even if the process itself is already unloaded 
from RAM.)

Normally a zombie process will disappear very quickly because the init process 
itself will remove it if no other program checks the return value.  If the 
zombie stays around, then it is usually because its parent process is still 
running, but is not checking the return value.  In that case you have to kill 
the parent in order to kill the zombie.

Eris Caffee