tracking down a warning

I can't find what's the statement causing this warning:

2008-11-19 14:45:34 CET WARNING:  nonstandard use of \\ in a string
literal at character 32 2008-11-19 14:45:34 CET HINT:  Use the
escape string syntax for backslashes, e.g., E'\\'.

I mean... I know how to fix it... but how can I find the statement?

Which is the right log config to tweak to get enough info to be able
to use grep on my code base without producing 2Gb logs in 5min?

BTW can this log config be tweaked dynamically? by connection etc...
or just in postgres.conf?

thanks

--
Ivan Sergio Borgonovo
http://www.webthatworks.it