[ruby-talk:7659] how to timeout as system call?

I need to be able to kill system commands which have run too long.  I
tried the following code to no avail:

     include Process
     #fork a process:
     kidpid = fork do
        puts "In child, pid = #$$"
        system('du /')  #or some command that takes a long time
     end
     puts "after fork: pid of parent is: #$$"
     #start a timer in the parent:
     killed = 0
     counter = 0
     afterpid = nil
     while (! afterpid = waitpid( kidpid, Process::WNOHANG ) )
        puts "inside loop after pid is: #{afterpid}"
        sleep 1
        counter = counter + 1
        puts counter
        if ( counter > 2 )  #should kill it after two seconds
           kill "SIGTERM", kidpid
           killed = 1
        end 
     end 
     puts "after pid is: #{afterpid}"



I find that if I replace the system call with a command internal to Ruby
(sleep 20) that it works as expected.  But spawning a system command seems
to be unkillable.  I also find that after the timeout happens and the kill
has been run, that the 'du /' is then not stoppable with ^C.

I do something very similar to this in perl code that
works...  the system command is killed and the program continues on its
way.

Phil