development, which has enabled him to focus on the Linux kernel full time.
Fortunately for all Linux users, Torvalds chose to distribute Linux under a
free software license called the GNU General Public License (GPL).
NOTE
You can search online for articles, interviews, and biographies that examine
Linus Torvald’s life and notable achievements.The GNU GPL is the brainchild of Richard M. Stallman, the founder of the
Free Software Foundation. Stallman, the famous author of the emacs editing
environment and GCC compiler system, crafted the GPL to ensure that
software that used the GPL for licensing would always be free and available
in source-code form. The GPL is the guiding document for Linux and its
ownership, distribution, and copyright. Torvalds holds the rights to the Linux
trademark, but thanks to a combination of his generosity, the Internet,
thousands of programmers around the world, GNU software, and the GNU
GPL, Linux will remain forever free and unencumbered by licensing or
royalty issues.
DISTRIBUTION VERSION AND KERNEL NUMBERING SCHEMA
There is a numbering system for Linux kernels, kernel development, and
Ubuntu’s kernel versions. Note that these numbers bear no relation to the
version number of your Ubuntu Linux distribution. Ubuntu distribution
version numbers are assigned by the Ubuntu developers, whereas most of
the Linux kernel version numbers are assigned by Linus Torvalds and his
legion of kernel developers.
To see the date your Linux kernel was compiled, use the uname command
with its -v command-line option. To see the version of your Linux kernel,
use the -r option. The numbers, such as 4.14.0-22-generic, represent the
major version (4), minor version (14), and patch level (0). The final number
(22-generic) is the developer patch level and in our context is what is
assigned by the Ubuntu developers.
Even minor numbers are considered “stable” and fit for use in production
environments. You will find only stable versions of the Linux kernel
included with this book. You can choose to download and install a beta
(test) version of the kernel, but doing so is not recommended for a system
destined for everyday use. Developers use beta kernels to test support of
new hardware or operating system features.Linux, pronounced “lih-nucks,” is free software. Combining the Linux kernel
with GNU software tools—drivers, utilities, user interfaces, and other
software such as the X.Org Foundation’s X Window System—creates a Linux