What is the meaning of cmake command lines

Question

I am trying to build a software following some instructions on line.

cd app
mkdir -p build/Release
cd build/Release
cmake ../..
make installpyplusplus && cmake .
make .

My questions:

1. What does "../.." after cmake do or mean?
2. What is the significance of the dot after make?
3. what will 'make installpyplusplus && cmake .' ?

Answer 1

The cmake application looks for one file in special, called CMakeLists.txt. So by running:

cmake ../..

It's like saying to cmake that the CMakeLists.txt is two directories below, like described by MERose.

The cmake command creates many files at your current working directory (CWD, the directory you ran the command from), and among them is a file called Makefile, which has rules about which files to compile/build/copy/write/whatever and how to do it.

So when you run:

make .

You are telling the make application that the Makefile file is at your CWD. It's the same as running:

make

That looks for the Makefile file at your CWD.

Concluding, . is the CWD, and .. is one level below.

EX: If your CWD is /Users/yourname/

• . represents /Users/yourname/
• .. represents /Users/
• ../. represents /Users/
• ../.. represents /

And so on...

what will 'make installpyplusplus && cmake .' ?

When you use && the commands will be executed sequentially if the first command returns true (exit status zero). So, in the case you said, make installpyplusplus will be run, and after it's done (it can create a CMakeLists.txt, I don't know what you are running), if it returns true, the command cmake . will be run, and if the CMakeLists.txt is there, it will run properly.

BONUS:

If you run:

make -j4

You will separate the build process in 4 instances (you can change 4 by anything you want)! Multi-threading magic will make it build faster if you have more than one processor core available :)