在C++SGI-STL3.3时看到了一个词copyright

/*
 * Copyright (c) 1996-1997
 * Silicon Graphics Computer Systems, Inc.
 *
 * Permission to use, copy, modify, distribute and sell this software
 * and its documentation for any purpose is hereby granted without fee,
 * provided that the above copyright notice appear in all copies and
 * that both that copyright notice and this permission notice appear
 * in supporting documentation.  Silicon Graphics makes no
 * representations about the suitability of this software for any
 * purpose.  It is provided "as is" without express or implied warranty.
 */

​​GPL协议​​

这个涉及到一个软件开源协议：GPL协议，即generic public foundation，即GNU通用许可证，他使用的是copyleft，即copyright的反义词。

Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed.

​​GNU官网​​

GNU即GNU is not Unix，发音和革奴类似，Linux里面很多软件都是靠GNU实现的，比如GCC，EGCS，Emacs，GNOME等等。

开源yyds