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<H1>Introduction to UNIX or Linux and the graphical desktop</H1>
<P> After you have logged in, you will be presented with a desktop showing
several icons and a panel that is similar to the Windows taskbar. It is
usually located at the bottom of the screen, but could also be located at
the top, or even one of the sides. Linux and its graphical interface, the X
window system, give a lot of choices and configuration options for the
desktop environment. The most commonly used desktops are the KDE desktop
and the GNOME desktop.
<P>For KDE, the panel may look something like:
<P><img src="images/kde-gnxbar.png">
<P>With GNOME, it might look like:
<P><img src="images/gnomebar-term.gif">
<P>
Some of the more important icons that you can click on are:
<UL>
<LI><img src="images/redhat-main-menu32.gif"> <b>The Red Hat main
menu</b>,or <img src="images/kmenu.png"> <b>The KDE main menu</b>, or <img
src="images/gnome-logo-icon32.gif"> <b>The GNOME main menu</b> - Like the MS
Windows start menu, it is used to logout, and to select programs to run,
some of which are in sub-menus. It is usually located at the left end of
the panel.
<P>
<LI> <img src="images/konsole.png"> or <img src="images/gnome-term.png">
<b>Terminal window</b> - A console window that allows you to type commands
to the UNIX shell. In UNIX, this is one of the most important applications.
Once you get used to it, you will find that after learning a few cryptic
two-letter UNIX commands, you will get things done much faster than going
through many levels of sub-menus with a GUI. You will create and run
GENESIS simulations by giving commands in a terminal window.
<P>
<P>If your taskbar doesn't have an icon for a terminal window, look for it
in the <b>System Tools</b> sub-menu of the Main Menu.
<P> <LI> <img src="images/redhat-web-browser32.gif"> <b>Web browser</b>, often
Mozilla. The bookmark feature of the browser can be used to set bookmarks
for GENESIS and other documentation.
<P> <LI> <img src="images/konqueror.png"> <b>Konqueror</b> - A fast and
light-weight web browser provided wth KDE that is good for reading
documentation.
<P>
<LI> <img src="images/khelpcenter.png"> <b>KDE help center</b> - Provides
links to information about the KDE desktop environment, KDE applications
on the KDE start menu, the UNIX manual ("man") pages, and GNU "info"
documentation.
<P>
<LI> <img src="images/kcontrol.png"> <b>KDE control center</b> - Used for
changing the configuration of the KDE desktop environment.
< P>
<LI> <img src="images/desktops.png"> <b>Desktops display</b> - Most Linux
desktop environments allow you to switch between multiple desktops, so
that your screen doesn't become too cluttered with applications and
terminal windows. For example, you could be running a GENESIS simulation
on one desktop, a couple of of browser windows open on another, and be
editing two or three files on a third. Here, the taskbar has been
configured to let you switch between four desktops by clicking with the
mouse.
</UL>
<P>
<A NAME="section-1.1"><H2>Getting around in UNIX and Linux</H2></A>
<P> The commands that you type within a terminal window are interpreted by
a <i>UNIX shell</i>. Your account will have been set up to use a
particular default shell. The most common shell used with Linux is
<i>bash</i>, a variation of the Bourne shell <i>sh</i>. Some prefer to use
<i>tcsh</i>, a variation of the Berkeley C shell <i>csh</i>. All of these
shells recognize the same common commands described below for creating,
navigating, or copying files between directories (in Windows-speak, "folders").
<P> When you first bring up a terminal window, you are placed in your home
directory. A few default configuration files with names starting with "."
have been set up for you, but otherwise your directory is empty. You can
get a listing of the current directory by using the <i>ls</i> command
(short for 'list'). This is like the DOS <i>dir</i> command, but you need
to specify some options (followed by a dash) to get details. To get a more
detailed listing including the "dot files", type "<tt>ls -lags</tt>".
<P>
To traverse to another directory you use the <i>cd</i> (change directory)
command. This command takes an argument of the directory you wish to
change to. Either an absolute or relative path argument can be specified.
Absolute paths begin at the "root" of the unix file system (/). Relative
paths begin from the currect working directory. For example, if you are in
your home directory, you can get to the next lower directory <i>mail</i> by
typing "<tt>cd mail</tt>". Typing "<tt>cd</tt>" by itself gets you to your
home directory. These shorthand symbols can be used to refer to commonly
used directories:
<UL>
<LI><b>~ </b> Your home directory.
<LI><b>. </b> The directory that you are currently in ("current working
directory").
<LI><b>.. </b> The directory immmediately above the current working directory.
</UL>
<P>
To create a directory, use the <i>mkdir</i> command, e.g. "<tt>mkdir
myScripts</tt>". Note that file and directory names in UNIX are
case-sensitive. "myScripts" is not the same as "myscripts".
<P>
To print the name of the current working directory you can use the
<i>pwd</i> (Print Working Directory) command.
<P> You can examine text files (such as all of our README files) using the
<i>more</i> command. This command will display a screenful of a lines at a
time. Pressing space bar displays the next bunch of lines, and pressing
"b" takes you back a screenful. Pressing "Enter" displays one additional
line. Pressing " ' " (apostrophe) returns you to the top of the file and
"q" will exit the more. For example, "<tt>more tutorial1.g</tt>" will
display the contents of the file "tutorial1.g", if it exists in the current
working directory. The "pipe" symbol " <tt>|</tt> " can be used to send
the output of one command into another. For example, try the command
"<tt>ls -lags ~ | more</tt>".
<P> Other useful commands are <i>rm</i>, meaning remove or delete, as in
"<tt>rm junk.mail</tt>", and <i>cp</i> to copy one file into another, as in
"<tt>cp tutorial3.g ~/myScripts/tutorials</tt>". The "-r" option lets you
recursively copy a directory with its contents, including any subdirectories.
For example, if GENESIS is installed in /usr/local/genesis, to make your copy
of the <i>genesis/Scripts/tutorials</i> directory, you would type
<pre>
cd /usr/local/genesis/Scripts
cp -r tutorials ~/myScripts
</pre>
<P>The <i>mv</i> command is used to rename a file or move it to a different
directory, instead of copying it.
<P>
The two most common text editors for UNIX are <i>vi</i> and <i>emacs</i>.
If you are not familiar with either editor, you may find it easier to learn
emacs. <A HREF="emacs.txt">Here</A> is a quick guide to using emacs.
For an even simpler text editor with built-in help, try <i>pico</i>
if it is installed. If you are using Linux with the KDE or GNOME desktop,
try <i>kedit</i> or <i>gedit</i>.
<P>
Documentation for most UNIX commands can be obtained with the <i>man</i>
command. For example "<tt>man ls</tt>" will tell you about all the options
for the <i>ls</i> command.
<P>
The standard program for reading email on UNIX is called <i>mail</i>. You
can find more about it with "<tt>man mail</tt>". The <i>pine</i> program
is much more user-friendly and has built in help. The Mozilla browser is
also good for reading mail.
<P>
The main source for information about Linux is the web site for The Linux
Documentation Project, <A
HREF="http://www.tldp.org/">http://www.tldp.org/</A>.
<P>If most of this is new to you, now would be a good time to open a
terminal window and try out some of the commands described above.
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