Shulou(Shulou.com)06/03 Report--

2.4 Linux Core Concept Knowledge

2.4.1 Free software and FSF

1) Free software

Simply understand, the core of free software is that there is no commercial software copyright restrictions, the source code is open, and it can be transmitted and modified without restriction.

Note: Free software emphasizes rights, not free. Freedom means Freedom, and free means Free, which is a completely different concept in English. For example: Red Hat Linux is free but not free, CentOS Linux is free and free.

Free software is about the user's freedom to run, copy, distribute, study, modify, and improve it. More precisely, free software gives its users four freedoms:

1. Freedom to run the software for whatever purpose.

2. There is freedom to study how the software works and to rewrite it as needed.

3. Freedom to redistribute copies.

4. There is freedom to improve the software and to distribute improvements to the public.

2) Free Software Foundation FSF

Free Software Foundation (FSF), which means Free Software Foundation in Chinese, was founded by Richard Stallman in 1984. FSF's main project is the GNU Project, whose goal is to build freely distributable and portable Unix-like operating system products. The GNU project itself produces major software including Emacs, gcc, bash, and gawk (GNU's awk).

2.4.2 GNU knowledge

GNU's full name is GNU's not Unix, meaning "GNU is not Unix." The GNU Project, also known as the GNU Project, was publicly launched by Richard Stallman in 1984 and is the main project of the FSF.

The GNU Unix-like operating system is a collection of applications, libraries, and development tools, such as Emacs editor, gcc compiler, bash command parser and programming language, and gawk (GNU's awk), plus a kernel for resource allocation and hardware management. GNU's own kernel Hurd is still under development, but it is still a long way from practical, so the GNU system has not caught on. The current GNU system is made up of the Linux kernel, some GNU project contributions, and other related programs. This combination is called the GNU/Linux operating system.

By the time the Linux kernel was released in 1991, the GNU Project had completed the development of all the necessary software in addition to the kernel. Under the efforts of Linus Torvalds and other developers, some GNU components were run on top of the Linux kernel, such as Emacs, gcc, bash, gawk, etc., which are still very important basic software in Linux.

2.4.3 GPL knowledge

1）GPL

The full name of GPL is General Plubic License, and its Chinese name is General Public License. It is one of the most famous open source license agreements. The most famous Linux kernel in the open source community is released under GPL license. The GPL license was created by the Free Software Foundation. Shortly after Richard Stallman launched the free software movement in 1984, the GPL was established in collaboration with others, which played a crucial role in promoting the development of free software.

The meaning of the GPL is simply understood. The core of the GPL license is to ensure that anyone has the freedom to share and modify free software. Anyone has the right to obtain, modify and redistribute the source code of free software, but must also give the modified source code.

Note: Although Linux is distributed under the GNU GPL license, the Linux kernel is not part of the GNU Project.

2）LGPL

The Lesser General Public License (LGPL) is more lenient than the GPL, allowing not to disclose all source code, providing a broader space for developing commercial software based on the Linux platform.

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