public static Map<String, String> getConfSystemProperties() {
    Map<String, String> systemProperties = new HashMap<String, String>();

    for (ConfVars oneVar : ConfVars.values()) {
      if (System.getProperty(oneVar.varname) != null) {
        if (System.getProperty(oneVar.varname).length() > 0) {
          systemProperties.put(oneVar.varname, System.getProperty(oneVar.varname));
        }
      }
    }

    for (Map.Entry<String, String> oneVar : overrides.entrySet()) {
      if (overrides.get(oneVar.getKey()) != null) {
        if (overrides.get(oneVar.getKey()).length() > 0) {
          systemProperties.put(oneVar.getKey(), oneVar.getValue());
        }
      }
    }
    return systemProperties;
  }
This method returns a mapping from config variable name to its value for all config variables
which have been set using System properties
common/src/java/org/apache/hadoop/hive/conf/HiveConf.java