Introduction & Overview

1. Support Level
2. Intended Audience
3. Obtaining an Account on VTAIX
4. Notation
   1. Key Representations
   2. Control Key Sequences
   3. Commands in the Body
   4. "1" vs "l"
5. Sample Files
6. VTAIX Accounts
7. Software Availability
   1. Editors
   2. Compilers
   3. Subroutine Libraries
   4. The SAS System

VTAIX is the Virginia Tech Computing Center's general UNIX system and runs on an IBM RS/6000 under AIX. AIX is an implementation of UNIX derived from both AT&T UNIX System V and 4.3 BSD (Berkeley Software Distribution).

Unless you request otherwise, the default shell or command interpreter will be the Korn (ksh) shell. The Bourne (sh) and C (csh) shells are also available and may be used in place of the Korn shell. The Shell Selection Summary describes similarities and differences among these shells.

The examples presented in this users guide assume use of the Korn shell. Where there are known differences between the Korn shell and the other two shells, alternative examples or notes will be included to explain how the examples should be modified to enable the function for the Bourne or C shell. Since some shell features, such as alias and history, are not available in the Bourne shell, it is recommended that you use the Korn or C shell as the default login shell for interactive applications.

Support Level

The service level for this software is SL2; the software is installed and some maintenance may be applied. The Computing Center maintains vendor documentation and local documentation may be available. Only certain consultants are familiar with the product. The consultants may need up to one working day to resolve basic problems, and may not be able to resolve complex problems. Short courses are not usually available.

Intended Audience

This user's guide is intended as a tutorial to assist you in learning how to use VTAIX. It is recommended that experienced UNIX users review the contents of the following sections and note differences between VTAIX and the system(s) with which you are already familiar:

• Introduction & Overview (this file)
• Accessing VTAIX
• Learning to Use UNIX and Consulting Assistance

If you are already familiar with Virginia Tech's VTVM1 mainframe system, you may wish to start with VTAIX for CMS Users which describes VM1-like utilities installed on VTAIX and similarities between these two environments.

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:

• Introduction & Overview (this file)
• Accessing VTAIX
• Learning to Use UNIX and Consulting Assistance
• Editing Files
• Working with Files
• Working with Directories
• Working in the Shell Environment
• Communicating with Other Users and Other Systems
• Individual User Security Concerns

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 Command Comparisons a useful starting point for beginning to use a UNIX system.

Programmers who are not familiar with UNIX development tools may find the following sections especially useful:

• Working in the Shell Environment Working with UNIX Programming Tools

In general, the information contained in this users guide should be applicable to most UNIX systems so that this guide can also be used as a tutorial for learning UNIX on other systems. If you are using this users guide with another system, substitute your machine name where VTAIX appears in this text. Additional exceptions include:

• Unique AIX commands (e.g., info) will not be found on other versions of UNIX or they may perform different functions.

• Since AIX is a hybrid of BSD and System V UNIX, 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 applications software. The C programming language will be found on most UNIX systems, but FORTRAN and Pascal 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. The SAS System will only be available on your machine if it has been licensed from SAS Institute Inc. for use on your machine.

• Unique Computing Center commands, such as "4help" and "ccdocs" will be found only on Computing Center supported machines.

• The vitutor may not be available on your system.

Should you encounter additional differences, vtaix.comments@vt.edu would appreciate your forwarding this information to us so that this guide can be revised as required. This users guide is not a complete description of the system software available on node VTAIX.CC.VT.EDU. Thus 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); the Computing Center 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.

Obtaining an Account on VTAIX

To obtain a VTAIX userid, complete the Application for VTAIX USERID. This form must be signed by the head of your department and returned to Information Resource Management via campus mail (0214) or fax (231-8649). New users will receive a default disk space allocation of 150 4k blocks.

Notation

mail  their_mai1id@their_Internet_address
	

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 AIX 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.

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"):

• ax01
• us1
• vtvm1
• vt100

• 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

Sample Files

The tutorial exercises included in this users guide are designed to use the Computing Center's mainframe UNIX system VTAIX. The sample files used in this class are located in the "xmp" sub-directory associated with userid aixstu00 on VTAIX. You can copy them to the "xmp" subdirectory of your VTAIX userid by entering the following commands:

mkdir   xmp
	cd      xmp
	cp  -r  ~aixstu00/xmp/*   .
	

Here ~/aixstu00 corresponds to the home directory specification for the files belonging to userid aixstu00. Use of tilda (~) as an abbreviation for the path to a home directory is supported only by the C and Korn Shells. If you are using the Bourne Shell, you will need to specify the full path to the directory containing the sample class files (e.g., currently this directory is /home/aixstu/aixstu00).

The "-r" option is used to request a recursive copy which results in copying each of the sub-directories and their contents as well as the files in aixstu00.

You must include the dot (".") which corresponds to your current working directory as part of the copy command. Unlike many other operating systems, such as PC/DOS, you must specify the target with the copy command; it does not assume the current directory if no "copy-to" target is specified.

The "mkdir" command is used to create a new sub-directory called "xmp" where you will store the example files used by the example exercises in this users guide. The "cd" command is then used to change into this directory so that you have direct access to these files (see Working with Directories for additional information and exercises for using directory commands). In future logon sessions, remember to use the "cd" command to change into the xmp directory so that you will have access to these files.

If you would like to complete these exercises and do not have a userid on VTAIX you can use anonymous ftp to copy the files from ftp.vt.edu; these files are located in /pub/cc/courses/unix. This directory contains three sub-directories (or folders) whose files should also be copied to your disk in order to complete all of these exercises. These directories are c, mixed_lang, and vi. "new.tar.Z" is a binary file and should be retrieved using the binary option of ftp. You will then need to issue the following commands to enable the some files for use during the class exercises:

  cc  my_source.c
	  chmod  a+x  argtest
	  chmod  a+x  filesize
	

VTAIX Accounts

The command for showing the amount of disk space available is:

quota
	

The du command can be used to display disk utilization. A dash (-) following a command is used to specify a command option or flag. The "-s" flag of the du command results in printing a summary total of disk blocks used and the "-a" flag results in printing the disk utilization for each file.

Observe the results of entering the following commands:

du  -a
	du
	du  -s
	

The df command can be used to display disk free space in a file system. This command is used primarily by system administrators. Observe the results of entering the following command:

df
	

Software Availability

AIX is a combination of both the System V and BSD version of UNIX. Thus you should find that most of the UNIX commands with which you are familiar, or which are documented in standard UNIX texts, are available.

Editors

The following popular full screen editors are currently available on VTAIX:

vi

a popular full screen UNIX editor found on most UNIX systems; see Editing Files for a description of the most commonly used vi commands.

GNU emacs

an emacs implementation from the Free Software Foundation, Inc. An online tutorial is provided as part of the product. To use the tutorial, enter the command "emacs", press <Ctrl-H> followed by the letter "t", and follow the online instructions. To exit emacs, press <Ctrl-X> and then <Ctrl-C>; if you attempt to exit from a file after having made changes, you will be asked to confirm that you do not wish to keep the changes you have made.

CMS-like xedit

a look alike of the Xedit command found on IBM VM/CMS systems.

Compilers

The following compilers are available for use on VTAIX:

xlf

FORTRAN

This compiler expects C source program files to end in the characters: ".f"

xlc

C Language

This compiler expects Fortran source program files to end in the characters: ".c"

xlp

Pascal

This compiler expects Pascal source program files to end in the characters: ".pas"

For additional information on these compilers and sample exercises, see Working with UNIX Programming Tools.

Subroutine Libraries

In addition to the standard libraries included with the compilers listed above, VTAIX has the following software libraries installed:

imsl

Mathematics and Statistical Subroutine Library from Visual Numerics. To use functions or subroutines in your program, simply insert the appropriate code in your program and include the -limsl option (to specify inclusion of these libraries) when you compile your program, e.g.:

xlf  prog_name.f  -limsl
	

For additional information on using these libraries, see IMSL - The International Mathematics Subroutine Library. (Virginia Tech Computing Center User's Guide, MT01).

essl

IBM's Engineering and Scientific Subroutine Library

The SAS System

The SAS System from SAS Institute Inc. is available for use on VTAIX.

To execute a SAS program on VTAIX, simply enter:

/usr/local/sas/sas    my_sas_program_name
	

where "my_sas_program_name" is the name of your SAS program file.

To create and submit programs interactively, enter:

/usr/local/sas/sas
	

endsas;
	

If you plan to use SAS extensively, you can eliminate the path in the above command by including "/usr/local/sas" as part of your default search path.

If you wish to use the X Windows System display mode of the SAS System, you must access VTAIX from a local machine which is running an X server. To exit from SAS when using the X Window System display mode, choose the Exit option from the File menu and then select OK to confirm that you do wish to terminate the current SAS session.