Overview

Relevant source files

• .github/FUNDING.yml
• CHANGELOG.md
• CMakeLists.txt
• README-cn.md
• README.md
• screenshots/example1.png
• screenshots/example2.png
• screenshots/example3.png
• screenshots/example4.png
• src/fastfetch.c
• src/fastfetch.h
• src/flashfetch.c
• src/modules/modules.h
• src/modules/options.h

Purpose and Scope

This page provides a comprehensive introduction to fastfetch, its architecture, and core capabilities. It covers the fundamental design patterns, main components, and execution model of the application. For detailed information about specific subsystems, refer to:

• Installation and Quick Start — Guide users through building, installing, and running fastfetch for the first time.
• Configuration Overview — Introduce the JSONC configuration system, preset files, and command-line argument parsing.
• Flashfetch Variant — Document the flashfetch variant, its differences from fastfetch, and use cases.

What is Fastfetch?

Fastfetch is a neofetch-like system information tool written primarily in C, with a focus on performance and customizability README.md1-16 It detects and displays hardware and software information about the host system in a visually formatted output.

Key Characteristics:

Aspect	Description
Language	C (mainly) CMakeLists.txt5
Platforms	Linux, macOS, Windows 8.1+, Android, FreeBSD, OpenBSD, NetBSD, DragonFly, Haiku, SunOS README.md16 CHANGELOG.md4-5
License	MIT License CMakeLists.txt10
Configuration	JSONC (JSON with comments) README.md106
Output Formats	Human-readable text with ANSI colors, JSON for machine consumption src/fastfetch.c18-53

Sources: README.md1-16 CMakeLists.txt1-10 src/fastfetch.c18-53 CHANGELOG.md1-5

Core Architecture Components

The FFinstance Global Singleton

The fastfetch application is built around a single global instance structure FFinstance that holds all configuration and state.

Data Structure Hierarchy

The FFinstance structure is defined in src/fastfetch.h41-45 and the global variable instance is declared as extern in src/fastfetch.h46

• FFconfig: Holds user-configurable options managed via FFOptionsLogo, FFOptionsDisplay, and FFOptionsGeneral src/fastfetch.h23-28
• FFstate: Maintains runtime state information, including the detected FFPlatform and terminal properties src/fastfetch.h30-39

Sources: src/fastfetch.h23-46

Application Lifecycle

The application follows an initialization, execution, and cleanup lifecycle. In fastfetch.c, the process typically involves:

1. Initialization: ffInitInstance() sets up the global instance src/flashfetch.c10
2. Start: ffStart() prepares the environment src/flashfetch.c20
3. Logo Rendering: ffLogoPrint() displays the ASCII or image logo src/flashfetch.c23
4. Module Execution: Modules are printed sequentially (e.g., ffPrintCPU, ffPrintGPU) src/flashfetch.c29-141
5. Cleanup: ffFinish() and ffDestroyInstance() restore the terminal and free resources src/flashfetch.c144-145

Sources: src/flashfetch.c8-147

Module System Architecture

Fastfetch implements a modular system where each piece of information (CPU, OS, etc.) is handled by a specific module.

Module Registry

Modules are registered in a global array ffModuleInfos src/fastfetch.h47 Each module is described by a FFModuleBaseInfo structure which contains its name and formatting arguments src/fastfetch.c28-33

Module Mapping

Fastfetch supports over 70 modules including Battery, CPU, Disk, GPU, Memory, OS, Packages, and Shell src/modules/modules.h1-77

Sources: src/fastfetch.h47 src/modules/modules.h1-77 src/fastfetch.c28-33

Platform Abstraction Strategy

Fastfetch achieves cross-platform support by providing platform-specific implementations for a common detection interface. The build system detects the platform using CMAKE_SYSTEM_NAME CMakeLists.txt28-50

Platform	Detection Implementation Scope
Linux	GNU/Linux and Kernel-specific logic CMakeLists.txt28-29
macOS	Apple Darwin specific APIs CMakeLists.txt48 CHANGELOG.md109
Windows	Windows 8.1 and later CMakeLists.txt109 CHANGELOG.md4-5
BSD	FreeBSD, OpenBSD, NetBSD, DragonFly CMakeLists.txt30-41
Other	Android, SunOS (Solaris), Haiku, GNU (Hurd) CMakeLists.txt42-47 CHANGELOG.md67-70

Sources: CMakeLists.txt28-50 CHANGELOG.md4-70

Build System and Feature Flags

The build process is managed by CMake CMakeLists.txt3 It uses a series of cmake_dependent_option and option flags to enable or disable features based on the target platform and available libraries.

• Library Detection: Uses PkgConfig to find dependencies like vulkan, wayland, or dbus CMakeLists.txt59-80
• Embedded Data: Options like ENABLE_EMBEDDED_PCIIDS allow embedding hardware databases directly into the binary CMakeLists.txt104
• Binary Variants: The BUILD_FLASHFETCH option controls whether the faster, neofetch-compatible variant is built CMakeLists.txt99

Sources: CMakeLists.txt1-104

Output and Presentation

Fastfetch is designed for both visual appeal and programmatic use.

• Logo Rendering: Supports built-in ASCII logos and image protocols like Sixel, Kitty, or iTerm README.md108
• Format Strings: Modules support custom format strings using placeholders (e.g., {name}, {version}) src/fastfetch.c38-43
• JSON Mode: Provides a structured JSON output via yyjson for integration with other scripts src/fastfetch.c18-53

Sources: src/fastfetch.c18-53 README.md108