single or duo core
 

I use RHEL 5 server , in /proc/cpuinfo , I found that 4 processor as following

more cpuinfo |grep processor
processor : 0
processor : 1
processor : 2
processor : 3

can advise how can I know how many is the physical CPU ? in my case , it is 4 physical CPU ? [/B]

Can't say from just that information. Don't grep everything out. The easiest way is to read the model number from /proc/cpuinfo and Google the specs.