log2c，即log to c（linux），类似java的log4j，根据配置文件的配置，生成linux c程序的log信息-log2c, the log to c (linux), similar to java' s log4j, according to the profile configuration, generate log information linux c program

interface that loggers should implement so that the stack can log to various loggers impl such as log4j, commons logging, sl4j, ..