ch07.htm

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caused a major shift in the computing community. As a result, the University of California
at Berkeley created its own version of UNIX, thereafter referred to as the <I>Berkeley
Software Distribution</I> or <I>BSD</I>. BSD was (and continues to be) extremely
influential, being the basis for many modern forms of commercial UNIX.</P>
<P>An interesting development occurred during 1980. Microsoft released a new version
of UNIX called <I>XENIX</I>. This was significant because the Microsoft product line
was already quite extensive. For example, Microsoft was selling versions of BASIC,
COBOL, Pascal, and FORTRAN. However, despite a strong effort by Microsoft to make
its XENIX product fly (and even an endorsement by IBM to install the XENIX operating
system on its new PCs), XENIX would ultimately fade into obscurity. Its popularity
lasted a mere five years. In contrast, MS-DOS (released only one year after XENIX
was introduced) took the PC world by storm.</P>
<P>Today, there are many commercial versions of UNIX. I have listed a few of the
them in Table 7.2.
<H4><FONT COLOR="#000077"><B>Table 7.2. Commercial versions of UNIX and their manufacturers.</B></FONT></H4>
<P>
<TABLE BORDER="1">
	<TR ALIGN="LEFT" rowspan="1">
		<TD ALIGN="LEFT"><I>UNIX Version</I></TD>
		<TD ALIGN="LEFT"><I>Software Company</I></TD>
	</TR>
	<TR ALIGN="LEFT" rowspan="1">
		<TD ALIGN="LEFT">SunOS &amp; Solaris</TD>
		<TD ALIGN="LEFT">Sun Microsystems</TD>
	</TR>
	<TR ALIGN="LEFT" rowspan="1">
		<TD ALIGN="LEFT">HP-UX</TD>
		<TD ALIGN="LEFT">Hewlett Packard</TD>
	</TR>
	<TR ALIGN="LEFT" rowspan="1">
		<TD ALIGN="LEFT">AIX</TD>
		<TD ALIGN="LEFT">IBM</TD>
	</TR>
	<TR ALIGN="LEFT" rowspan="1">
		<TD ALIGN="LEFT">IRIX</TD>
		<TD ALIGN="LEFT">Silicon Graphics (SGI)</TD>
	</TR>
	<TR ALIGN="LEFT" rowspan="1">
		<TD ALIGN="LEFT">DEC UNIX</TD>
		<TD ALIGN="LEFT">Digital Equipment Corporation</TD>
	</TR>
</TABLE>
</P>
<P>These versions of UNIX run on proprietary hardware platforms, on high-performance
machines called <I>workstations</I>. Workstations differ from PC machines in several
ways. For one thing, workstations contain superior hardware and are therefore more
expensive. This is due in part to the limited number of workstations built. PCs are
manufactured in large numbers, and manufacturers are constantly looking for ways
to cut costs. A consumer buying a new PC motherboard has a much greater chance of
receiving faulty hardware. Conversely, workstation buyers enjoy more reliability,
but may pay five or even six figures for their systems.</P>
<P>The trade-off is a hard choice. Naturally, for average users, workstations are
both impractical and cost prohibitive. Moreover, PC hardware and software are easily
obtainable, simple to configure, and widely distributed.</P>
<P>Nevertheless, workstations have traditionally been more technologically advanced
than PCs. For example, onboard sound, Ethernet, and SCSI were standard features of
workstations in 1989. In fact, onboard ISDN was integrated not long after ISDN was
developed.</P>
<P>Differences also exist depending upon manufacturer. For example, Silicon Graphics
(SGI) machines contain special hardware (and software) that allows them to generate
eye-popping graphics. These machines are commonly used in the entertainment industry,
particularly in film. Because of the extraordinary capabilities of the SGI product
line, SGI workstations are unrivaled in the graphics industry.</P>
<P>However, we are only concerned here with the UNIX platform as it relates to the
Internet. As you might guess, that relationship is strong. As I noted earlier, the
U.S. government's development of the Internet was implemented on the UNIX platform.
As such, today's UNIX system contains within it the very building blocks of the Net.
No other operating system had ever been so expressly designed for use with the Internet.
(Although Bell Labs is currently developing a system that may even surpass UNIX in
this regard. It is called Plan 9 from Bell Labs; Plan 9 is covered in Chapter 21,
&quot;Plan 9 from Bell Labs.&quot;)</P>
<P>Modern UNIX can run on a wide variety of platforms, including IBM-compatible and
Macintosh. Installation is typically straightforward and differs little from installation
of other operating systems. Most vendors provide CD-ROM media. On workstations, installation
is performed by booting from a CD-ROM. The user is given a series of options and
the remainder of the installation is automatic. On other hardware platforms, the
CD-ROM medium is generally accompanied by a boot disk that loads a small installation
routine into memory.</P>
<P>Likewise, starting a UNIX system is similar to booting other systems. The boot
routine makes quick diagnostics of all existing hardware devices, checks the memory,
and starts vital system processes. In UNIX, some common system processes started
at boot include</P>

<UL>
	<LI><FONT COLOR="#000000">Sendmail (electronic mail services)<BR>
	<BR>
	</FONT>
	<LI><FONT COLOR="#000000">RPC (remote procedure calls)<BR>
	<BR>
	</FONT>
	<LI><FONT COLOR="#000000">TCP/IP (networking protocols)</FONT>
</UL>

<PRE></PRE>
<P>After the system boots successfully, a login prompt is issued to the user. Here,
the user provides his or her login username and password. When login is complete,
the user is generally dropped into a shell environment. A <I>shell</I> is an environment
in which commands can be typed and executed. In this respect, at least in appearance,
basic UNIX marginally resembles MS-DOS. Navigation of directories is accomplished
by changing direction from one to another. DOS users can easily navigate a UNIX system
using the conversion information in Table 7.3.
<H4><FONT COLOR="#000077"><B>Table 7.3. Command conversion table: UNIX to DOS.</B></FONT></H4>
<P>
<TABLE BORDER="1">
	<TR ALIGN="LEFT" rowspan="1">
		<TD ALIGN="LEFT"><I>DOS Command</I></TD>
		<TD ALIGN="LEFT"><I>UNIX Equivalent</I></TD>
	</TR>
	<TR ALIGN="LEFT" rowspan="1">
		<TD ALIGN="LEFT"><TT>cd &lt;directory&gt;</TT></TD>
		<TD ALIGN="LEFT"><TT>cd &lt;directory&gt;</TT></TD>
	</TR>
	<TR ALIGN="LEFT" rowspan="1">
		<TD ALIGN="LEFT"><TT>dir</TT></TD>
		<TD ALIGN="LEFT"><TT>ls -l</TT></TD>
	</TR>
	<TR ALIGN="LEFT" rowspan="1">
		<TD ALIGN="LEFT"><TT>type|more</TT></TD>
		<TD ALIGN="LEFT"><TT>more</TT></TD>
	</TR>
	<TR ALIGN="LEFT" rowspan="1">
		<TD ALIGN="LEFT"><TT>help &lt;command&gt;</TT></TD>
		<TD ALIGN="LEFT"><TT>man &lt;command&gt;</TT></TD>
	</TR>
	<TR ALIGN="LEFT" rowspan="1">
		<TD ALIGN="LEFT"><TT>edit</TT></TD>
		<TD ALIGN="LEFT"><TT>vi</TT></TD>
	</TR>
</TABLE>



<BLOCKQUOTE>
	<P>
<HR>
<FONT COLOR="#000077"><B>Cross Reference:</B></FONT><B> </B>Readers who wish to know
	more about basic UNIX commands should point their WWW browser to <A HREF="http://www.geek-girl.com/Unixhelp/"><B>http://www.geek-girl.com/Unixhelp/</B></A>.
	This archive is one of the most comprehensive collections of information about UNIX
	currently online.<BR>
	Equally, more serious readers may wish to have a handy reference at their immediate
	disposal. For this, I recommend <I>UNIX Unleashed</I> (Sams Publishing). The book
	was written by several talented UNIX wizards and provides many helpful tips and tricks
	on using this popular operating system. 
<HR>


</BLOCKQUOTE>

<H3><FONT COLOR="#000077"><B>Say, What About a Windowing System?</B></FONT></H3>
<P>UNIX supports many windowing systems. Much depends on the specific platform. For
example, most companies that have developed proprietary UNIX systems have also developed
their own windowing packages, either partially or completely. In general, however,
all modern UNIX systems support the X Window System from the Massachusetts Institute
of Technology (MIT). Whenever I refer to the X Window System in this book (which
is often), I refer to it as <I>X</I>. I want to quickly cover X because some portions
of this book require you to know about it.</P>
<P>In 1984, the folks at MIT founded Project Athena. Its purpose was to develop a
system of graphical interface that would run on workstations or networks of disparate
design. During the initial stages of research, it immediately became clear that in
order to accomplish this task, X had to be hardware independent. It also had to provide
transparent network access. As such, X is not only a windowing system, but a network
protocol based on the client/server model.</P>
<P>The individuals primarily responsible for early development of X were Robert Scheifler
and Ron Newman, both from MIT, and Jim Gettys of DEC. X vastly differs from other
types of windowing systems (for example, Microsoft Windows), even with respect to
the user interface. This difference lies mainly in a concept sometimes referred to
as <I>workbench</I> or <I>toolkit</I> functionality. That is, X allows users to control
every aspect of its behavior. It also provides an extensive set of programming resources.
X has often been described as the most complex and comprehensive windowing system
ever designed. X provides for high-resolution graphics over network connections at
high speed and throughput. In short, X comprises some of the most advanced windowing
technology currently available. Some users characterize the complexity of X as a
disadvantage, and there is probably a bit of merit to this. So many options are available
that the casual user may quickly be overwhelmed.


<BLOCKQUOTE>
	<P>
<HR>
<FONT COLOR="#000077"><B>Cross Reference:</B></FONT><B> </B>Readers who wish to learn
	more about X should visit the site of the X Consortium. The X Consortium comprises
	the authors of X. This group constantly sets and improves standards for the X Window
	System. Its site is at <A HREF="http://www.x.org/"><B>http://www.x.org/</B></A>.<BR>
	
<HR>

<HR>
<FONT COLOR="#000077"><B>NOTE:</B></FONT><B> </B>Certain versions of X can be run
	on IBM-compatible machines in a DOS/Windows Environment. 
<HR>


</BLOCKQUOTE>

<P>Users familiar with the Microsoft platform can grasp the use of X in UNIX by likening
it to the relationship between DOS and Microsoft Windows 3.11. The basic UNIX system
is always available as a command-line interface and remains active and accessible,
even when the user enters the X environment. In this respect, X runs on top of the
basic UNIX system. While in the X environment, a user can access the UNIX command-line
interface through a shell window (this at least appears to function much like the
MS-DOS prompt window option available in Microsoft Windows). From this shell window,
the user can perform tasks, execute commands, and view system processes at work.</P>
<P>Users start the X Window System by issuing the following command:</P>
<PRE><FONT COLOR="#0066FF">startx
</FONT></PRE>
<P>X can run a series of <I>window managers</I>. Each window manager has a different
look and feel. Some of these (such as twm) appear quite bare bones and technical,
while others are quite attractive, even fancy. There is even one X window manager
available that emulates the Windows 95 look and feel. Other platforms are likewise
emulated, including the NeXT window system and the Amiga Workbench system. Other
windowing systems (some based on X and some proprietary) are shown in Table 7.4.
<H4><FONT COLOR="#000077"><B>Table 7.4. Common windowing systems in UNIX.</B></FONT></H4>
<P>
<TABLE BORDER="1">
	<TR ALIGN="LEFT" rowspan="1">
		<TD ALIGN="LEFT"><I>Window System</I></TD>
		<TD ALIGN="LEFT"><I>Company</I></TD>
	</TR>
	<TR ALIGN="LEFT" rowspan="1">
		<TD ALIGN="LEFT">OpenWindows</TD>
		<TD ALIGN="LEFT">Sun Microsystems</TD>
	</TR>
	<TR ALIGN="LEFT" rowspan="1">
		<TD ALIGN="LEFT">AIXWindows</TD>
		<TD ALIGN="LEFT">IBM</TD>
	</TR>
	<TR ALIGN="LEFT" rowspan="1">
		<TD ALIGN="LEFT">HPVUE</TD>
		<TD ALIGN="LEFT">Hewlett Packard</TD>
	</TR>
	<TR ALIGN="LEFT" rowspan="1">
		<TD ALIGN="LEFT">Indigo Magic</TD>
		<TD ALIGN="LEFT">Silicon Graphics</TD>
	</TR>
</TABLE>

<H3><FONT COLOR="#000077"><B>What Kinds of Applications Run on UNIX?</B></FONT></H3>
<P>Many types of applications run on UNIX. Some of these are high-performance applications
for use in scientific research and artificial intelligence. I have already mentioned
that certain high-level graphics applications are also common, particularly to the
SGI platform. However, not every UNIX application is so specialized or eclectic.
Perfectly normal applications run in UNIX, and many of them are recognizable names
common to the PC and Mac communities (such as Adobe Photoshop, WordPerfect, and other
front-line products).</P>
<P>Equally, I don't want readers to get the wrong idea. UNIX is by no means a platform
that lacks a sense of humor or fun. Indeed, there are many games and amusing utilities
available for this unique operating system.</P>
<P>Essentially, modern UNIX is much like any other platform in this respect. Window
systems tend to come with suites of applications integrated into the package. These
include file managers, text editors, mail tools, clocks, calendars, calculators,
and the usual fare.</P>
<P>There is also a rich collection of multimedia software for use with UNIX, including
movie players, audio CD utilities, recording facilities for digital sound, two-way
camera systems, multimedia mail, and other fun things. Basically, just about anything
you can think of has been written for UNIX.
<H3><FONT COLOR="#000077"><B>UNIX in Relation to Internet Security</B></FONT></H3>
<P>Because UNIX supports so many avenues of networking, securing UNIX servers is
a formidable task. This is in contrast to servers implemented on the Macintosh or
IBM-compatible platforms. The operating systems most common to these platforms do