How to make cmake output to the "build" directory?

Question

I'm using cmake to compile a C++ project, and I want cmake to generate all the output files(metafiles like Makefile used to create binaries) in the build folder. I've checked all the answers in How do I make cmake output into a 'bin' dir?, none of them worked for me(suprisingly!). Files are generated in the root folder instead of in the build folder, what's wrong here? I guess I must have missed something.

Code Structure

➜  cmake-test tree .
.
├── CMakeLists.txt
└── hello.cpp

0 directories, 2 files

CMakeLists.txt

# Specify the minimum version for CMake
cmake_minimum_required(VERSION 3.11)

# Project's name
project(hello)

# Set the output folder where your program will be created
set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/build)
set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/build)
set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin)

# The following folder will be included
include_directories("${PROJECT_SOURCE_DIR}")

add_executable(hello ${PROJECT_SOURCE_DIR}/hello.cpp)

Build Commands and Outputs

➜  cmake-test cmake .

-- The C compiler identification is GNU 8.2.0
-- The CXX compiler identification is GNU 8.2.0
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Configuring done
-- Generating done
-- Build files have been written to: /home/searene/CLionProjects/cmake-test

➜  cmake-test ls

bin  CMakeCache.txt  CMakeFiles  cmake_install.cmake  CMakeLists.txt  hello.cpp  Makefile

cmake version

➜  cmake-test cmake --version

cmake version 3.11.4

CMake suite maintained and supported by Kitware (kitware.com/cmake).

OS

Linux

Answer 1

The usual way to do this, rather than changing variables to set the path, is simply to create the output directory, change to it, and run cmake from there. So instead of cmake . you usually have cmake .. or similar.

I understand the initial impulse to say "But I expect my build system to write output somewhere else." But CMake is not usually used in the way you were initially expecting, and other people who run your CMake build won't expect what you were expecting, so it's probably best to just use the built-in, default behavior, which is to put the output wherever cmake was run.

Put another way: You are fighting against the tool. Don't do that.