Datasheet

Chapter 1: An Overview of Red Hat Linux 5
Support for many old computer components get carried from one release to the next. There are
old PCs running Red Hat Linux today as routers (to route data between your LAN and the
Internet), firewalls (to protect your network from outside intrusion), and file servers (to store
shared files on your LAN) — with maybe an Ethernet card or an extra hard disk added.
At this point, you may feel that Linux is something you want to try out. This brings us to the
basic question: What is Linux?
What Is Linux?
Linux is a free operating system that was created by Linus Torvalds when he was a student at
the University of Helsinki in 1991. Torvalds started Linux by writing a kernel — the heart of
the operating system — partly from scratch and partly by using publicly available software.
(For the definition of an operating system and a kernel, see the sidebar “What Is an Operating
System?” later in this chapter.) Torvalds then released the system to his friends and to a
community of “hackers” on the Internet and asked them to work with it, fix it, and enhance it.
It took off.
CROSS-REFERENCE: See Chapter 14 for a discussion about the difference between hackers (who
just like to play with computers) and crackers (who break into computer systems and cause damage).
Today, there are hundreds of software developers around the world contributing software to
the Linux effort. Because the source code for the software is freely available, anyone can work
on it, change it, or enhance it. Developers are encouraged to feed their fixes and improvements
back into the community so that Linux can continue to grow and improve.
On top of the Linux kernel effort, the creators of Linux also drew on a great deal of system
software and applications that are now bundled with Linux from the GNU software effort
(GNU stands for “GNU is Not UNIX”), which is directed by the Free Software Foundation
(
www.gnu.org). There is a vast amount of software that can be used with Linux, all of
which includes features that can compete with or surpass those of any other operating system
in the world.
If you have heard Linux described as a free version of UNIX, there is good reason for it.
Although much of the code for Linux started from scratch, the blueprint for what the code
would do was created to follow POSIX standards. POSIX (Portable Operating System
Interface for UNIX) is a computer industry operating system standard that every major version
of UNIX complied with. In other words, if your operating system was POSIX-compliant, it
was UNIX. See the next section describing Linux’s roots in the UNIX operating system.
Linux’s Roots in UNIX
Linux grew within a culture of free exchange of ideas and software. Like UNIX — the
operating system on which Linux is based — the focus was on keeping communications open
among software developers. Getting the code to work was the goal, without much concern