Printed below is the GNU General Public License (the GPL or copyleft), under which Linux is licensed. It is reproduced here to clear up some of the confusion about Linux's copyright status -- Linux is not shareware, and it is not in the public domain. The bulk of the Linux kernel is copyright © 1993 by Linus Torvalds, and other software and parts of the kernel are copyrighted by their authors. Thus, Linux is copyrighted, however, you may redistribute it under the terms of the GPL printed below.
Copyright (C) 1989, 1991 Free Software Foundation, Inc.
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Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed.