by September 6, 2001 0 comments

The short technical explanation is that Linux is a
multi-user, multi-tasking operating system that runs on many platforms, including Intel
processors, 386 and higher. It implements a superset of the POSIX standard. Linux
inter-operates well with other operating sy How does Linux compare to other
operating systems?

Linux is based on the POSIX operating system standard,
which was derived from Unix when Unix was still a product of Unix Software Laboratories.
Today, Unix is a available to the OS vendors only when their software passes a series of
tests and they pay a licensing fee. One Linux vendor, Caldera, is in the process of
securing a Unix brand for their Linux product.

Unix is compatible with Linux at the system call level,
meaning most programs written for either Unix or Linux can be recompiled to run on the
other system, with little or no modifications. While traditional Unix runs on more types
of hardware than Linux, it has paid the price of over 25 years of baggage to make this
possible. That means Linux will run faster than Unix on the same hardware. Moreover, Unix
has the disadvantage of not being free.

MS-DOS, like Linux, has a hierarchical file system. But it
only runs on x86-based processors, does not support multiple users or multi-tasking, and
it is not free. Also its interoperatility with other operating systems is poor and it does
not include networking software, development programs, or many of the utility programs
included with Linux.

Microsoft Windows offers some of the graphics capabilities
of Linux and includes some networking capabilities, but it suffers all other handicaps of
MS-DOS.

Windows NT is available for the Digital Alpha, as well as
x86 processors, but it suffers many of the disadvantages of Windows. It has had much less
time in the field (meaning less time to work out bugs), and it has a rather large price
tag attached to it.

Apple’s operating system for the Macintosh runs only
on the Mac. It also suffers from a lack of development tools and less-than-smooth
interoperability with other systems. (Note: Apple has made Linux available for
NuBus-based
PowerMacs and is expected to do the same for PCI bus-based Macs as well.)

Whence Linux?

Where did Linux come from? First, and possibly most
important, Linux has its roots on the Internet. It was developed by a very diverse group
of people. This diversity includes knowledge and experience. It also includes geography,
and spans virtually all of the earth’s surface. In order to work together, this group
needed a quick and efficient way to communicate. The Internet was that tool and as Linux
was the system of choice for these people, the necessary tools to use the Internet
appeared early on in Linux. Those tools continue to evolve and be honed, as Linux
development continues.

While the Linux kernel was an independent development
effort, many of the applications have been culled from the best available software. For
example, the C compiler is gcc from the Free Software Foundation’s GNU project. This
compiler is commonly used by people using Hewlett-Packard’s HP/UX and Sun Microsystem’s
Solaris operating systems. What is included with Linux?

When you get Linux, you get everything. That is,
everything you would expect to be included with an operating system, and more. Each Linux
distribution includes hundreds of packages offering a full and rich set of utilities,
connectivity tools, and a development environment.

Here is a short list to give you the general idea:

  • Development software including compilers, assemblers, and
    debuggers
  • Text editors and text formatting programs
  • Usenet news readers and e-mail agents
  • World Wide Web development tools, Web servers and browsers
  • Graphics creation and manipulation tools

When told that Linux has mostly everything you need, people
tend to come up with something obscure or something they don’t really want, just to
test the limits. For example, you might say you needed an Ada compiler for Linux. Well,
the answer is yes, there is an Ada compiler included with Linux.

Let’s look at an example of where Linux could be used
and what is needed to make it fit. The example I am thinking of is a small Internet
service provider. (A small ISP to simplify the example–not because Linux isn’t
capable of bigger things.) The ISP used by Specialized Systems Consultants, publishers of Linux
Journal
, has 14 Linux systems and supports hundreds of users simultaneously.

To offer this sort of service you need:

  • Internet connectivity
  • Multi-port, dial-up service
  • PPP and possibly SLIP connectivity
  • Usenet news
  • Mail routing
  • Web server
  • Online backups

Most of these capabilities are inherent in Linux. The
others come with the hardware needed to support the capability.

For example, multi-port dial-up service is supported with
serial communications products from Comtrol, Cyclades, Digi, Equinox, Gtek, Maxpeed, and
others. Or, if you want to try an external option, terminal servers work fine with Linux.
Our ISP uses the Cyclades option and another local ISP uses Livingston PortMasters
connected to the Linux hosts over Ethernet.

PPP and SLIP are integral parts of Linux. Their support and
the number of channels supported are configuration options when you build the Linux
kernel. Besides regular Unix login/password security, support for PAP and CHAP are
available. Usenet news and Internet mail are also included. The
software to support news includes the standard systems available on Unix platforms. INN
seems to be the most popular. Mail is handled by sendmail for most systems. While not as
capable, smail is also available and may be a better fit for low-end configurations.

Various Web servers are included with Linux. At SSC we
chose to use Apache because it is reliable and efficient. The fact that we handle about
100,000 hits per day on a 486 system with 16 MB of RAM tends to support our choice. For
those needing a secure Web server, they are not free but are available.

Finally, backups. In order to be a respected ISP you need
to offer continuous service and you can’t lose your customer’s data. After all,
that’s why they pay you. Linux includes the standard Unix utilities to do backups
(tar, cpio, and backup/restore). There are also commercial products offering additional
capabilities.

This doesn’t mean Linux comes with every application
you need to run your office or your entire business. However, while it may not be
included, it may be available. For example, databases, word processors, spreadsheets, and
sophisticated graphics programs are available for Linux. You will see names like
Applixware, Corel, and Empress in the Linux camp when you look for these sorts of
applications.

Who uses Linux?

A recent survey conducted by iX, a Unix and
networking magazine based in Germany, showed some startling results. Linux is used at work
by 45 percent of the readers. Solaris 1 and 2 taken together come second with 36 percent,
followed by HP-UX with 27 percent. Of companies with fewer than 50 employees, 56 percent
use Linux; it is used by 38 percent of firms with more than 1,000 employees. In addition,
60 percent of the readers use Linux on their computers at home.

Other places Linux has significant market penetration is in
Web servers and as the operating system of choice in universities. Also, many individuals
who’ve realized the need to learn Unix for career advancement have decided to use
Linux on their home computer as a training tool.

Linux is also becoming popular in embedded and turnkey
applications, including Internet firewalls, routers, and Point of Sale (POS) systems.

Give Linux a try

If you have read this far, you must have some serious
interest. Give Linux a try. You can download a copy from the Internet or use the CD-ROM
with this issue of PC Quest. You’ll find that Linux is a first rate operating
system with capabilities beyond what you expect from more expensive products.

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