Running status of a process

[Prasanta Sadhukhan <Prasanta.Sadhukhan@Sun.COM>]

Hi,

Can anyone point as to how can I obtain the information whether a 
non-child process is still running?

I tried waitpid(pid, &status, WNOHANG) but always receive return value 
as -1 with errno as ECHILD.
Since the processes I am waiting for is not the child of this process 
from where I am calling waitpid() (ie, they are independant processes), 
it might be a valid error but what is the other alternative?

Regards
Prasanta