Commands

% Start a tracer
dbg:tracer().

% Tell it to trace the current process and its children
dbg:p(self(), [c,sos]).

% Tell it to trace our test function
dbg:tpl(testmod,test,2,[]).  % Tells it to trace testmod:test/2

% Call module to see test message
testmod:test(1,2).

% Note that it shows the parameters.  You can trace my_server:handle_call to see state of calls.
% You can also trace a great many other things besides just calls.  Very handy.  See the dbg docs.

% If you want to go really crazy, the ET module has facilities to graphically inspect traces. Have fun!

testmod.erl

-module(testmod).

-export([test/2]).

test(_A,_B) -> ok.