Building Software¶

Build systems automate the process of compiling source code into executables or libraries.
They manage dependencies, compiler flags, and installation steps, making builds portable and repeatable.

General Flow¶

Source Code → Configuration → Build Files → Compilation Installation

Source Code¶

Contains .c, .cpp, .h, and related source files.
Includes metadata files that describe how to build (e.g., CMakeLists.txt, configure.ac, Makefile.am).

Configuration¶

Detects system settings, compilers, and libraries.
Generates platform-specific build files (like Makefiles or Visual Studio projects).

Build¶

Uses generated build files to compile and link the code.

Installation¶

Copies binaries, headers, and other files to system directories.

Example: CMake¶

Configuration → Build → Install

# create build dir
mkdir build; cd build

# Step 1: Configure (generate build system files)
cmake .. -DCMAKE_INSTALL_PREFIX=/path/to/prefix

# (Optional) Use ccmake for more transparency
ccmake ..

# Step 2: Build
make -j

# Step 3: Install
make install

Note

If you’re unsure what variables you can tweak in a cmake project, you can launch a terminal user interface by using ccmake in place of cmake

Files involved:

CMakeLists.txt: Describes targets, dependencies, and options.
build/: Directory containing generated Makefiles or project files.

Typical flow:

CMakeLists.txt → CMake generates Makefiles → make builds → make install

Example: GNU Autotools¶

Bootstrap → Configure → Build → Install

# Step 1: Generate configuration scripts (for maintainers)
autoreconf -i

# Step 2: Configure (generate Makefiles)
./configure --prefix=/path/to/prefix

# Step 3: Build
make -j$(nproc)

# Step 4: Install
make install

Files involved:

configure.ac: Defines project metadata and system checks.
Makefile.am: High-level Makefile template.
Makefile.in and configure: Generated intermediate files.

Typical flow:

configure.ac + Makefile.am → autoreconf → configure → Makefiles → make → make install

Comparison Summary¶

Step	CMake	Autotools
Input file(s)	`CMakeLists.txt`	`configure.ac`, `Makefile.am`
Configuration tool	`cmake`	`autoreconf`, `configure`
Output files	Makefiles or project files	`Makefile`
Build command	`cmake --build` / `make`	`make`
Install command	`cmake --install` / `make install`	`make install`
Portability focus	Cross-platform (Windows/Linux/macOS)	Primarily Unix-like systems