public String getEnvironmentVariable(String name) {
    if (name.equalsIgnoreCase(CliConstants.CONFIG_EXECUTOR)) {
      return activeExecutorClassName;
    }

    EnvironmentVariableHandler handler = getAppropriateHandler(name);
    if (handler == null)
      return null;

    return handler.getEnvironmentVariable(name);
  }
Gets the value of an environment variable.
@param name environment variable name
@return value of the environment variable. Returns null if the variable is not set.
samza-sql-shell/src/main/java/org/apache/samza/sql/client/cli/CliEnvironment.java