This is the constructor method.
It stores the output stream as member data.
Arguments
proc_name a string containing the name of the child process
args the argument list obtained from argv
returns none
spawnChild
spawnChild ( self, args )
This is a method to spawn a child process.
It uses the pseudo-terminal module to fork a process.
Turning off ECHO is important to avoid multiple writes to the screen.
Arguments
args the argument list obtained from argv
returns none
transferIstr
transferIstr ( self )
This function listens to output of the child process, filters it,
and prints to the screen if appropriate. In this base class, it
has no functionality and should be over-written in the derived class.