DESIGN.txt

*) vgdb parameters
vgdb [-vgdb-{env}] [-vi|-c] {target and parameters}

-vgdb-{env} will overwritten envvar named "VGDB_{env}", e.g.
	export VGDB_DEBUG=1
	export VGDB_PORT=33089
	vgdb cpp1 
	=>
	vgdb -vgdb-debug -vgdb-port:33333 cpp1
-vi
	a mark that indicates it's called by vi; ignore to start vi
-c 
	client mode

*) Debug vgdb via log:

Start vgdb in command mode:
	export VGDB_PORT=44444
	export VGDB_DEBUG=1
	vgdb -vi cpp1
or 
	vgdb -vgdb-debug -vgdb-port:44444 -vi cpp1
(set VGDB_DEBUG to use the fix port)

Command from client side:
	export VGDB_PORT=44444
	vgdb -c ".init"
	vgdb -c "b main; r; n"
	vgdb -c ".p m"
	vgdb -c "q"

*) Debug vgdb via vgdb
Start vgdb in command mode:
	vgdb -vgdb-debug vgdb -vgdb-port:44444 -vi cpp1

Note: 
- outer vgdb debug the perl program 'vgdb' using a random port (as it's not specified in envvar or argument)
- inner vgdb debug the C++ program 'cpp1' using port 44444 
- Note: inner env will inherit outer env (e.g. -vgdb-debug is inheritted by inner)

*) Abnormal quit or killed
if no response from vgdb or vgdb is forcely killed, then it may not run, please try:
kill process of: perl gdb vgdb gvim
find and kill the program occupied the vgdb port: 
	netstat -anp | grep 30899
	(on windows, use "netstat -ano")
	kill {pid}

("netstat -p" is to show process id (pid) using the port, on MS Windows use "-o" instead)