-- Run `scons --all` to build source and `test` file. A executable file `TestMain`,
-which is used to run the unit test, will be generated under `test`
+ To build folder `src/` and `test/` and `main.cpp`. `libtracker.a` , `main`,
+ and `test/TestMain` will be generated. Run `TestMain` to run all the unit
+ test
+
+- Run `scons -c` or `scons --all -c`