A comprehensive understanding of the GNU Program

What operating systems do you use now? Recently, Linux seems to be popular. Do you know GNU/Linux? The GNU program, also known as the German plan, was launched by Richard Stallman in September 27, 1983. The goal of the GNU program is to create a completely free operating system. Richard Stallman was first created in net. this message was published on the unix-wizards news group with an article explaining why the program was initiated, such as the GNU declaration, one reason is to "reproduce the spirit of cooperation and mutual assistance between the software community ".

GNU contains three terms,

GPL: GNU General Public License)

LGPL: GNU loose Public License (GNU Lesser General Public License), formerly called GNU Library General Public License (GNU Library General Public License );

GFDL: the GNU Free Documentation License.

The freedom here is not free of charge. It has nothing to do with the price, but the use of software is free for all users. GPL achieves this goal through the following channels:

1. It requires the software to be released in the form of source code, and requires that any user can copy or publish the software to another user in the form of source code.

2. if your software uses a part of any software protected by GPL, the software inherits the GPL software and becomes the GPL software, that is, the source code must be released along with the application.

3. GPL does not exclude the commercial packaging and release of Free Software, nor is it restricted to the packaging and release of other non-free software on the basis of free software.

Because GPL is difficult to be used by commercial software, it requires that the code of the library that calls it also be GPL, all open, and released together, and cannot be directly connected. Therefore, GNU later launched the LGPL license.

If you are planning to use Linux in your project, you must understand two of the above two licenses, GPL and LGPL ..

Similarities:

Because GPL and LGPL are both established by the Free Software Foundation, they are very similar. They all have the important features of Copyleft:

The term copyleft is derived from the slang term Copyleft In the GNU project. Copyright indicates the Copyright, that is, the meaning of the non-profit Copyright. It refers to the following terms in the open source code license: No one or company can copy the source code of the software protected by GPL/LGPL. After modification, protect these changes, even if their modifications may make the software better than the original version. Once a piece of code is protected by GPL or LGPL, the Code itself and all modifications made to it must be made public to the people and organizations interested in it. If a third party modifies and releases the code, the modified code and the original code must be disclosed to the person who accepts the code.

Differences:

The results of source code release under GPL and LGPL license protection are very similar. Any changes made to the old code must be made public to those who want to know the code, the only difference is whether private copyright code can be connected to open source code. LGPL allows entities to connect private code to open source code, and can publish these merged binary code in any form. Only these codes are dynamically connected. When using dynamic links, even when a program calls a function in the function library during running, the application itself and the function library are different entities)

In this way, you will understand the GNU program.