Overview & Intended Audience
This document is intended as a tutorial to assist you in learning how to use
Unix. An implementation of Unix is used as the operating system
on the VT ARC System X,
SGI Altix (Inferno, Inferno2, and Cauldron), and
SUN (Dante) systems.
The information contained in this users guide should also be
applicable to Linux, OS-X, and most other Unix systems so that this guide can also be used
for learning Unix on other systems as well as the VT ARC systems.
A Unix shell provides you with an interface for interacting with the Unix kernel.
The examples presented in this users guide assume use of the
BASH (bash) shell which is the
default shell used on the VT ARC accounts unless you had specifically requested
a different shell on your account application.
The Bourne (sh),
Korn (ksh),
and C (csh)
shells are also available on the VT ARC systems.
Where there are known differences between the BASH shell and these
shells, alternative examples or notes are included to explain
how commands or the examples should be modified to enable the function for the
Bourne, Korn, or C shell.
The Shell Selection Summary describes
similarities and differences among these shells.
Since some shell features, such as alias and history, are not available in the Bourne
shell, it is recommended that you use the BASH, Korn, or C shell as your
login shell for interactive applications.
It is recommended that experienced Unix users review the contents of the
following sections and note differences between the Unix systems you are
familiar with and the information presented here:
If you have not used Unix before, but are already familiar with the IBM mainframe
VM/CMS, DEC VAX/VMS, or PC-DOS operating system(s), you may find the table of
Unix Command Comparisons
a useful starting point for beginning to use a Unix system.
If you have never used a Unix system before, it is recommended that you
become familiar with the information provided in each of the following
sections and complete each of the examples as they are presented:
Programmers who are not familiar with Unix development tools may find
the following sections especially useful:
In general, the information contained in this document should be
applicable to most Unix systems; exceptions may include:
- Some commands (e.g., info and the joe editor) may not be found on
other implementions of Unix or they may perform different functions.
- Command options may differ from those found on your system. In general, most options
used in the examples of this users guide should perform the indicated
function on all Unix systems. Known differences are indicated within
notes of the text.
- Availability of application software. The C programming language
will be found on most Unix systems, but a Fortran compiler and other applications described here
may not be installed on your system. Utility libraries described in the users guide may
not be available, may contain different routines, or may be located in
directories other than those listed here.
Should you encounter additional differences, use the
Website Feedback Form
to send us information about these differences. We
would appreciate your forwarding this information to us so that this
guide can be revised to best assist individuals using the VT ARC systems.
This users guide is not a complete description of the ARC systems;
there are many commands and command options available which are not described
herein. See the online system documentation for a complete description
of the system capabilities.
It is recommended that you read some of the many
popular books on Unix; VT ARC recommends
A Practical Guide to the Unix System by Mark G. Sobel as a beginning text.
In addition to providing a very good introduction to
the Unix operating system, it includes an appendix detailing the use
of the most common Unix utility programs.
Notation
All Unix based systems have case sensitive commands.
That is, it makes a difference whether you enter
items in upper or lower case.
When we show Unix command syntax, we will indicate items
that you must enter "as is" in the required case.
When we show items for which you must supply a value,
we will include the term "your_", "my_", or "their_".
For example,
to compile a C language source program and specify the name for the resultant
executable program,
you might see:
cc -o my_executable my_c_source.c
Key Representations
The "less than" (<) and "greater than" (>) symbols are used
as pairs surrounding
the names of keys or key sequences to distinguish them
from Unix commands or symbols.
For example, <Return> is used to refer
to the key used to end a line and submit a command (or begin a new line).
It may be represented on your keyboard by "Return", "Ret", "Enter",
"Newline", or a bent arrow pointing left.
Whenever you see <Return> in the text,
press the key corresponding to this function.
Note: In C source code examples <stdio.h> and <time.h> are used in
the standard fashion to indicate C programming language include files.
Note: The individual symbols "<" and ">" or
the pair ">>" are used in the standard Unix sense
to indicate the Unix redirection characters.
Control Key Sequences
Unix based systems such as Unix use control key sequences
indicated by "Ctrl-C",
where C can be any letter from A to Z.
You might see a sentence like this:
You can interrupt execution of
the "xyz" command by pressing
Ctrl-C.
To issue Ctrl-C, hold down the CTRL key while
you press the lower case "c" key.
All control key sequences are shown with an upper case letter.
You may always use the lower case letter.
Note: Do not press the "-" key as part of the control key sequence; the
dash is used within the notation to separate "Ctrl" from the
specification of the key which is to follow.
Note: You do not have to press <Return> following control key sequences.
Commands in the Body
If the text is easy to follow and clear, the command will not be set
off in any special way in the body.
Example 1:
To display a list of your files, use the ls command.
If the text is complex, a command or filename may be enclosed in quotes.
Example 2:
To display a list of your files and their access permissions,
enter the command "ls -l".
"1" vs "l"
Some display and print environments do not distinguish well between the
number one ("1") and the lower case letter L ("l").
If your display does not distinguish between these characters, the
following words should be interpreted as containing the number one
("1"):
If your display does not distinguish between these characters, the
following words should be interpreted as containing the letter lowercase
L ("l"):
- imsl library
- l -- move cursor right when using the vi editor
- -l -- an option to a Unix utility program
- ls
- learn
- xlc, xlf, and xlp
- link
- lint
- lp or lpr command
- login and logout
Software Availability
You should find that most of the Unix commands with which you are familiar,
or which are documented in standard Unix texts, are available on the VT ARC systems.
Text Editors
The following popular full screen editors are currently available on the VT ARC systems:
- vi
- a popular full screen text editor found on most Unix systems; see
Using the "vi" Editor
for a description of the most commonly used vi commands.
For more information on using the vi editor, enter: man vi
- joe
- a full screen text editor that uses "Ctrl" key sequences in its operation;
To start using this editor, simply enter the command "joe" at the Unix prompt.
Once you have started joe, you can display a Ctrl key function summary chart by pressing and holding down
the Ctrl key, simultaneously pressing the "K" key, releasing both of these keys, and then pressing the "H" key.
For more information on using the joe editor, enter: man joe
The ed and ex editors are also available.
Compilers
The following compilers are available for use on the VT ARC systems.
See the compiler documentation for individual systems for details on their use:
- System X
- SGI Altix (Inferno, Inferno2, and Cauldron)
- SUN (Dante)
For addition information on using these compilers with sample exercises, see
Working with Unix Programming Tools
Software Applications
For information about software applications available at Virginia Tech and on the VT ARC systems, see
Application Software For Research Computing at Virginia Tech.
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