许可
GNU GENERAL PUBLIC LICENSE Version 3, 29 June 2007 Copyright (C) 2007 Free Software Foundation, Inc. https://fsf.org/ Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed. Preamble The GNU General Public License is a free, copyleft license forsoftware and other kinds of works. The licenses for most software and other practical works are designedto take away your freedom to share and change the works. By contrast,the GNU General Public License is intended to guarantee your freedom toshare and change all versions of a program--to make sure it remains freesoftware for all its users. We, the Free Software Foundation, use theGNU General Public License for most of our software; it applies also toany other work released this way by its authors. You can apply it toyour programs, too. When we speak of free software, we are referring to freedom, notprice. Our General Public Licenses are designed to make sure that youhave the freedom to distribute copies of free software (and charge forthem if you wish), that you receive source code or can get it if youwant it, that you can change the software or use pieces of it in newfree programs, and that you know you can do these things. To protect your rights, we need to prevent others from denying youthese rights or asking you to surrender the rights. Therefore, you havecertain responsibilities if you distribute copies of the software, or ifyou modify it: responsibilities to respect the freedom of others. For example, if you distribute copies of such a program, whethergratis or for a fee, you must pass on to the recipients the samefreedoms that you received. You must make sure that they, too, receiveor can get the source code. And you must show them these terms so theyknow their rights. Developers that use the GNU GPL protect your rights with two steps:(1) assert copyright on the software, and (2) offer you this Licensegiving you legal permission to copy, distribute and/or modify it. For the developers' and authors' protection, the GPL clearly explainsthat there is no warranty for this free software. For both users' andauthors' sake, the GPL requires that
