problem killing a process with its pid

[Richard Yang]

I have been trying to kill the process by pulling natd.pid
below are 3 typical examples among a couple dozens I tried

kill -9 $(natd.pid)
Illegal variable name

kill -9 '/var/run/natd.pid'
kill: Arguments should be jobs or process id's

cat /var/run/natd.pid | kill -9
(no error returned, but natd process is still up)


could someone help?
thanks.


-- 

Best Regards

Richard Yang
richardyang at richardyang.net
kusanagiyang at gmail.com