There are rules in files named 'Makefile'. You can consider to learn how make works. To compile only halui, just do these steps below:
1. Go to your project directory
2. Go to src directory located in your porject root directory
3. run this: make ../bin/halui
You can compile only halui.cc with these steps. But before doing it, be sure you already configured the source tree.
halui executable is being outputted at bin directory in your project root directory. This is why you are should run ../bin/halui rule in Makefile located in your src directory. You can build many single executables with this combination. If you wanna learn what does the Makefile include, just do these:
1. type this to your shell in src directory: make
2. After typing 'make', press space to give space character
3. Press TAB two times.
It is gonna show the rules. You can build axis, mdi, milltask, halui, iocontrol etc. in the same way.