On Sat, Nov 7, 2009 at 11:34 AM, Eric Liang <eric.l.2046@gmail.com> wrote:
Hi all,
I'm trying some web frameworks, Erlyweb, Erlang-web and Nitrogen till
now.  Do jobs like this are usually not in smooth waters, and then debug
is necessary. But this time, I found couldn't get the yaws' debug info.

I've tried run yaws by --debug flag, and even modify the yaws.app file(
set the debug env variable), both did not work. :( .  The log files in
/var/log/yaws are still *.access/auth.log/report.log/trace.http, no
other debug output file. I check the content of these files, it looks
like there are no debug info in them. So my question is: how can I get
the yaws' debug output? Did I missed something?

How about

yaws --interactive --tracetraf --traceout --tracehttp --debug

This runs yaws interactively and shows all kinds of debug and trace info right on stdout.
 
As a newbie in web development, I'm curious how to debug yaws itself,
would you mind tell me something about that? Also, any other suggestions
will be appreciated. Thanks in advance.

Why do you feel you need to debug yaws? Are you seeing problems with it? I assume you want to debug your own code running under yaws, not yaws itself.

For the ultimate in debugging, learn about the Erlang dbg module. If you have Francesco's and Simon's "Erlang Programming" O'Reilly book <http://oreilly.com/catalog/9780596518189>, read chapter 17 thoroughly, and then read it again. (If you don't have the book, get it.) Try every example and do every exercise at the end of the chapter. I've never run a debugger on any Erlang code I've written, ever, because with the dbg module and tracing, I've never needed a traditional debugger.

--steve