Hi, I want to output the value of variables in my user space module for the debugging purpose, I try to use printf or Dprintk(actually it is a macro definiton of printf). But I can't find where the output goes. It doesn't appear on the console windows , nor does it be logged in the /var/www/log/messages. If I use write(req->sock,...), I can find the output information in the web page. I enabled CONFIG_TUX_DEBUG and rebuild the kernel and set the Dprintk and all_userspace in /proc/sys/net/tux. But Dprintk or printf still doesn't work. Usually printf will output the information to the screen, does TUX changes the output direction of printf? I know for TUX itself, it use Dprintk based on printk since it is a kernel space dameon, but for all user space module programs, Dprintk is implemented by printf. How can printf print information to syslog? You can find the definition of Dprintk for user modules in tuxmodule.h in /usr/include. I found another very strange thing in tuxmodule.h, just look this(pasted from tuxmodule.h). TUX_DEBUG is defined 0 by default, e.g. Dprintk do nothing. So should I change the value of TUX_DEBUG from 0 to 1 before I compile my user space module program if want to output some debugging information? #define TUX_DEBUG 0 #if TUX_DEBUG # define Dprintk(x...) do { printf(x); fflush(stdout); } while (0) #else # define Dprintk(x...) do { } while (0) #endif Liang