How to show Erlang call stack?

Question

I need to debug some module in foreign system. The module has public function foo() - how can I know place (module and function name) from which foo() given module

Answer 1

Here is my code for doing this:

format_stack_entry(S) ->
    {Module,Fun,Arity,[{file,File},{line,Line}]}=S,
    io_lib:format("{~p,~p,~p,[{file,~p},{line,~p]}",[Module,Fun,Arity,File,Line]).
stacktop([Top|_]) ->
    Top.
ancestor(N) ->
    {_,Stacktrace}=erlang:process_info(self(),current_stacktrace),
    ancestor(N+1,Stacktrace).
ancestor(1,S) ->
    format_stack_entry(stacktop(S));
ancestor(N,[_|T]) ->
    ancestor(N-1,T).

info(Format)      -> io:format(lists:concat([ancestor(2),Format,"\r"])).
info(Format,Args) -> io:format(lists:concat([ancestor(2),Format,"\r"]),Args).

Lists is a custom module in the system. Use your foo module instead.