Hi!


1. Running the mud under DBX.

Best way to use DBX is to run the mud under DBX, and let it crash.
Two ways to do this (we'll use aberd for example)
Most of this guide applies to gdb as well. Read this, this is good stuff!

interactive:

(a)	% dbx aberd
	Reading symbolic information...
	Read 20748 symbols.
	(dbx) run
		[mud will start to run]

more transparent:

(b)	% dbx -r aberd
	Reading sumbolix information...
	Read 20748 symbols.
		[mud starts automatically]

in (a) you may specify arguments to aberd after run.. (i.e. run -x -y would
be same as "aberd -x -y". in (b) simply add arguments after aberd.

see man dbx for more


p.s. if you have a core file from a previous crash, you may check where
the program crashed (assuming you have the binary that produced the core)
by loading it as:

	% dbx aberd core

(the core will usually be in ../data/core)

Once loaded, you may use any of the commands in 2.


2. Examining a crash point.

Once the mud crashes, some info will be displayed.. If that is not enuff
to pinpoint the problem, type "where". It will give you a traceback, the
topmost function being the function in which the program crashed.

At the same type, you may type "list". This displays portions in the code
where the crashpoint is believed. Note the line number may not be accurate
when you type "list" (since it's been advanced, and you usually wanna see
what's before and after the crash) so you may need to use "list 10, 20" for
example to list between lines 10 and 20.

see help list/where for more


3. Examining variables.

You may want to check some variables. Easiest way is to type "dump", which
will display all variables. You may also type:

	display [variable]

to display a particular variable. Note that if you have a variable x,
display *x, display &x, and display x may give different results. Check
a C manual for what *, & means.. You can even check the member of a structure
by simply typing "display structure->member"...

see help display/dump for more

NOTE: with gdb you can also use print [Variable]

4. A word about TRACE

tracing is fun with small programs, but it is pretty much useless with 
aberd, since a full trace would take over an hour just to get to the motd.

however, you may trace simpler stuff.. like "trace homecom" will print
a message every time "homecom()" is called. Or "trace var" where var
is a variable, will tell you every time that variable changes.

see help trace for more.


5. Breakpoints

If you want the progra to stop at various points, you can do something like:

	stop in homecom()

and it will stop whenever homecom() is executed and present you with a
(dbx) prompt. You can examine the state at that point, or type "cont" to
continue execution. You can also stop when a variable changes values, etc.
You can clear breakpoints with "clear".

see help clear/stop for more.

NOTE: with gdb on linux you can do it with 'break homecom'. then you can step
      through the code with 'next'. To remove it you use clear like in 
      mentioned above

      You can also stop somewhere in the function by specifying the line 
      number.

-val