Chinese Computer Culture of GNU and Its Operating Systems (III)

What is GNU?

Reference from the official website (http://www.gnu.org/) Definition:

GNU is a Unix-like operating system composed of free software. You can choose to install a Linux kernel-based GNU system completely composed of free software.

The GNU project was founded in 1984 to develop a complete GNU system. The GNU name is "GNU's Not Unix !" Recursive acronyms. The pronunciation of "GNU" is g'noo, which has only one syllable and is similar to "grew". However, replace r with n.

A Unix-like operating system is a collection of software consisting of a series of applications, system libraries, and development tools, plus a kernel for resource allocation and Hardware Management.

Use the Linux kernel.Such a combination is the GNU/Linux operating system. There are already millions of people using GNU/Linux, but many of them call it "Linux" by mistake ".

At the same time, we can find that the GNU Operating System is mentioned on the official website of GNU. The ultimate goal of GNU is to build a complete Operating System Using Free Software. Before the Linux kernel starts, remember that Linux is only a kernel, such as a Unix system kernel, this is one of the reasons why the GNU/Linux system we usually use is called a Unix-like system. Before the Linux kernel starts, the GNU program has completed most of the Software except the operating system kernel, including a shell, C language library, and a C language compiler. But remember that the Linux kernel is not part of the GNU program.

GPL

As described earlier, you may not have to mention the GPL, GNU General Public License Agreement (in English: GNU General Public License, gnu gpl or GPL) (for details, see: http://www.fsf.org /):

GPL, written by stoman, is used for the GNU program. It is based on earlier versions of GNU Emacs, GDB, and GCC licenses. These licenses all contain some GPL copyright ideas, but only for specific procedures. Stoman's goal is to create a license that can be used within four seas, so as to benefit many source code sharing programs. Here I have reproduced an easy-to-understand summary from Wikipedia for the GPL terms (Original: http://zh.wikipedia.org/wiki/GNU%E9%80%9A%E7%94%A8%E5%85%AC%E5%85%B1%E8% AE %B8%E5%8F%AF%E8%AF%81 ).

Rights granted

The terms and conditions of this GPL apply to anyone who receives the work under the GPL (that is, the "License recipient "). Any license recipient who accepts these Terms and Conditions shall be authorized to modify, copy, re-release, or deduct the version of the work or work. The license recipient can charge for this service, and vice versa. This is the biggest difference between GPL and other free software licenses that prohibit commercial use. Stallman believes that free software should not limit its commercial use, while GPL clearly illustrates this.

However, GPL stipulates that the issuer cannot restrict the rights granted by GPL. For example, this prohibits the issuance of software in a silent (passive) protocol or contract. The issuer under GPL also agrees that the patents used in the software can be used in other GPL software.

Copyleft

GPL does not grant unlimited rights to the license recipient. The re-issuance right requires the license receiver to open the source code of the software and all modifications. You must use GPL as the license to copy and modify the version.

These requirements are copyleft, which is based on the copyright of the work. Because of its copyright ownership, the license recipient has no right to modify or re-issue the license unless it has a copyleft clause. If someone wants to exercise the rights normally prohibited by law, just agree to the GPL clause. On the contrary, if someone issues software that violates GPL (for example, not open source code), he may be sued by the original author.

Copyleft uses copyright law to do the opposite: copyleft gives denied rights, rather than many restrictions stipulated by copyright law. This is also why GPL is called the "hacked copyright law.

Many GPL software vendors bundle source code with executable programs. The other method is to provide source code with physical media (such as CD) as the carrier. In practice, many GPL software are released on the Internet, and the source code can also be obtained in many ways.

Copyleft takes effect only when the program resends the row. Modifications to the software may not be made public or open source code, as long as they are not released. Note that copyleft is only effective for the software, but not for the software output (unless the software itself is output ). However, this may be changed in GPL version 3.

GPL is a license

GPL is designed as a license rather than a contract. In Anglo-American law countries, there is a clear legal difference between licenses and contracts: contracts are guaranteed by contract law, while GPL is guaranteed by copyright law as a license. However, this is not the case in many countries that adopt the European law system.

GPL principle is simple: under copyright law, you do not have the right to comply with the terms and conditions of GPL. Without GPL, the copyright law takes effect as the default clause, rather than entering the public domain.

Free Software

"Free Software" is a matter of rights, not a matter of price. To understand this concept, freedom should be "freedom" in "Freedom of Speech", rather than "free" in "free beer ".

Free Software is related to the user's freedom to run, copy, release, research, modify, and improve the software. More precisely, free software gives software users four freedom:

• The freedom to run the software, regardless of the purpose ).
• There is a study on how the software runs and the freedom to rewrite the software as needed (one of the Freedom ). Before obtaining the software source code.
• We have the freedom to re-release copies, so that you can use this to come to dunqin (Freedom 2 ).
• The freedom to improve the software and release improvements to the public can benefit the entire community (Freedom 3 ). Before obtaining the software source code.

GNU Operating System

Components that constitute the GNU Operating System:

Project name	Purpose
Coreboot	The predecessor, LinuxBIOS, provides hardware initialization similar to BIOS.
GRUB	Multi-OS Startup Program
GNU Hurd	System Kernel
Bash	Shell
GCC	Programming Language compiler, supporting c ada fortan java and other languages

In this way, a system is barely ready to go on the road. As for the desktop selection, there are various options, and there is not enough information to show which desktop will be used.

GNU HURD

GNU Hurd is a series of daemon processes based on the GNU Mach or L4 microkernel. This daemon eventually forms the GNU operating system. GNU plans to develop GNU Hurd from 1990 and release it as a GPL-compliant free software. Hurd aims to surpass the Unix kernel in terms of functionality, security, and stability while maintaining its compatibility. Therefore, Hurd complies with POSIX standards.

"HURD" is an indirect recursive abbreviation from "HIRD of Unix Replacing Daemons", where "HIRD" indicates "HURD of Interfaces Representing Depth ".

GNU/HURD-based GNU operating system release

• Bee GNU/Hurd
• Debian GNU/Hurd
• Superunprivileged.org GNU/Hurd Live CD