Thank you for the answers , but ...
I know exactly how to kill process in oracle (alter system)
and in unix (kill -9),
but the problem is that i want to write a pl/sql
procedure that kills unix process - i pass the pid
as a parameter and it will go to OS and 'kill -9'
the process there !.
Why ?
Because in some situations oracle only marks the session
for kill and does not actually kill the process
in OS for hours - in example when replication
between two nodes is stuck the only solution
to resume the snapshot jobs is to kill processes
in unix and not in oracle.
Please help me if anyone knows the solution.

thanks.