code: protected static void inferConfiguration ()
      {
          // first set up our provider
          String provider = null;
          try {
              provider = System.getProperty("log_provider");
              if (provider != null) {
                  Class<?> lpclass = Class.forName(provider);
                  _provider = (LogProvider)lpclass.newInstance();
              }
  
          } catch (SecurityException se) {
              // ignore security exceptions; we're just running in a JVM
              // that won't let us read system properties
  
          } catch (Exception e) {
              _provider.log(WARNING, "samskivert",
                            "Error instantating log provider " +
                            "[class=" + provider + ", error=" + e + "].");
          }
  
          // now set our log level
          try {
              String lstr = System.getProperty("log_level");
              if (!StringUtil.isBlank(lstr)) {
                  int level = levelFromString(lstr);
                  if (level != -1) {
                      _provider.setLevel(level);
                  } else {
                      _provider.log(WARNING, "samskivert",
                                    "Unknown log level requested " +
                                    "[level=" + lstr + "].");
                  }
              }
  
          } catch (SecurityException se) {
              // ignore security exceptions; we're just running in a JVM
              // that won't let us read system properties
          }
      }
docs: Checks the <code>log_provider</code> system property to see if a
  log provider has been specified. Installs it if so. Checks the
  <code>log_level</code> system property to see if a default log
  level has been specified. Sets it if so.