Hi All, As my understanding, with libevent, any io should be non_blocking, and here comes my dumb q;-) I want log stuffs(trace) to a disk file in my comm callback, so I open a file like below, but I didn't get any write event to call back. I am using Ubuntu Dapper and my target system is Solaris 10. Using stdout worked. Thanks. Arthur ---------------------     fdmsg = open(glbCfg.msg_file, O_WRONLY|O_CREAT|O_APPEND|O_NONBLOCK, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);     if(fdmsg<0)     {       err(-1, "Can't open file to write %s", glbCfg.msg_file);     }     //fdmsg = fileno(stdout);         if(fcntl(fdmsg, F_SETFL, O_NONBLOCK)==-1)     {       err(-1, "fcntl");     }         rcd = io_new_sink(fdmsg);     printf("rcd %p %d\n", rcd, fdmsg);