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Host Operating Systems 203
The SAS® System under UNix® Operating Systems and Derivatives
Sal/y Painter, SAS Institute Inc.,
cary NC
The schedula' is sometimes referred to as lhe kernel.
ABSTRACT
~ operating systems and derivatives offer
many features that are quite powerfuJ. Coupled with
extensive capabilities oflhe SAS System, a powerful
tool for data analysis and management has been
created. This paper will introduce features of UNIX
operating systems and derivatives and features of the
SAS System that combine to form a unique data
processing task.
The file system is the organizing structure fcx- data.
It is perhaps the most important part of the system.
The file system goes beyond simply a place to store
data; it provides lhe means of organizing lhe layout
of the data stcx-age in complex ways.
UNIX operating systems and derivatives have three
basic typeS of files:
• directories
Introductio n to UNIX Operating
Systems and Derivatives
The fmt UNIX operating system was developed in
the late 1960s with the goal of creating an environ-
ment to promote efficient programming developmenL One impressive feature of the UNIX operating
systems and derivatives is the ability to port the
system from one hardware environment to another.
Rather than being specialized systems for one particular piece of hardware, or haldware vendor, the
UNIX operating systems and derivatives can be easily modified to function efficiently on many hardware platforms.
The UNIX operating systems and derivatives are
divided into three major areas:
• scheduler
• fdesystem
• shell.
The scheduler is responsible for making the operating
system a multitasking and multiuser system. That is,
more than one user can be on the system and performing many tasks at the same time. The scheduler
manages the computer resources among the current
processes. Each process is handled separately, although to the users on the system it seems as if the
tasks are running simultaneously.
The scheduler is also responsible for controlling the
swapping of programs from memory to disk. Most
current UNIX operating systems and derivatives now
• special ftles
• ordinary files.
Directories can be best understood by using the analogy of a filing cabineL The drawers in the cabinet
are the subdirectories, and the folders within the
drawers are the files.
Special files are those that the scheduler needs in
order to set up the environmenL The fde names of
special files are usually prefixed with a period, and
are sometimes referred to as hidden files since they
will not be displayed when using the standard Is
command.
The shell is the command interpreter. It is just a
utility program and not properly a part of the system;
however, it is the part that you see. The shell listens
totheterminalandtraDSlatesrequestsintocommands
that the scheduler can understand.
There are currendy three popular shells:
• the Bourne shell (sh)
• the C shell (csh)
• the Kmt shell (ksh).
Each shell offers slighdy different features and capabilities. The Kom shell is compatible with the
BoiU1le shell. The C shell is noL
employ the strategy of paging rather than swapping.
With paging, programs are still moved from memory
to disk, but they are moved in a fixed page size rather
than by moving the entire program.
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1/0 Redirection
Most system commands either read from standard
input (stdin) or write to standard output (stdout). By
default, standard input and output are defmed as the
terminal. You can redirect your input and output
using the operating system. For example, the cat
command is used to display standard inpuL You can
use input redirection (< ) to specify a system fl.le as
input, rather than stdin. For example:
eat< mylile
Output redirection (>) is used to specify another
destination for the output from a command rather
than stdouL For example:
Is > contents
This sends the output from the Is command to the fde
named contents rather than to stdouL
Pipes
UNIX operating systems and derivatives uses the
pipe facility (I) to allow one command to read the
output from another command. For example, to display the current users a page at a time, you would use
the following:
wbolmore
Shell Scripts
A shell script, or shell program, is just a collection of
system commands that are grouped together for a
particular !ask. 'These commands are then stored in
a file that has been marked as executable.
The SAS System under UNIX
Operating Systems and Derivatives
Today, there are many "flavors" of the standard
UNIX operating system: HP-UX, AIX, Ultrix, and so
on; The SAS System currently supports the following platforms:
• HP-UX™
The SAS System allows many features of UNIX
operating sys~s and derivatives to be used during
your SAS SCSSJon. An excellent example is the ability 10 use pipes to send and receive information from
the SAS session 10 the operating system. This capability is available through the FILENAME statement
in the SAS System.
The syntax is
FILENAME r~~erer pipe 'system_com mand';
If the fileref is used in the SAS FILE statement, then
the SAS output is sent 10 the system command. If the
fileref is used in the INFILE statement, the OUtput of
the system command is read by the SAS System.
To produce a listing of all users currently logged on
to the system, you would use the foUowing code:
FILENAME JN PIPE 'WHO';
DATA WHO;
JNFILEJN;
JNPUT WHO SCHAR80.;
RUN;
PROC PRINT DATA=WHO;
TITLE
'USTING OF CURRENTLY
LOGGED USERS';
RUN;
The pipe facility can also be used to send information
from the SAS System as input 10 a system command.
For example, you can execute the following code 10
send data directly 10 a printer.
FU.ENAME OUT PIPE 'lp -dc2700jll';
DATA .NULL..;
FILE OUT;
PUT 'DID IT WORK?';
RUN;
Some practical examples using the pipe facility can
• SunOS™
be found in "The SAS System under UNIX and
• UL1RIX™
Derivative Operating Systems: New Features, New
Power" in Proceedings of the Fourteenth Annual
·~
• 00/UX™
• DomainOS 10.2.
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SAS Users Group lnter1101ionDl Conference .
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Future of the SAS System under
UNIX Operating Systems and
Derivatives
The SAS System is continually evolving into a more
powerful data management system. The features
discussed so far are available with Release 6.03 of
the SAS System. With the coming of Release 6JJ/
under UNIX operating systems and derivatives, more
enhancements have been added.
SAS/CONNECfTM is a new product for Release 6.06
under MVS and CMS and Release 6.07 under UNIX
platfonns. Originally known as the Micro-to-Host
Link, SAS/CONNECT has added new features and
capabilities to the original product The product will
continue to develop into a complete cooperative processing tool. For example, a workstation running the
UNIX operating system or a derivative can be logically attached to a MVS mainframe to access production data stored in a DBMS table. This enables you
to combine the power and storage facilities of a
mainframe system with the flexibility of your workstation system.
Another new feature that will be available in Release
6.07 is the SAS/GRAP~ Interactive Graphics Editor. This enhancement to SAS/GRAPH software
will allow you to interactively modify graphics produced with a graphics procedure or the DATA Step
Graphics Interface. To invoke the editor, bring up
the graphics window and type EDIT or select Edit
from the pull-down menu.
Some functions available with the Graphics Editor
are the ability to
• move or resize an object
• create, delete, or duplicate an object
• save modifications in a graphics catalog
• add text
of UNIX operating systems and derivatives. This
product will provide capabilities for exploratory data
analysis through interactive graphs.
SAS/INSIGHT software resembles the ~ software product currently available on Macintosh hardware. Unlike JMP software, SAS/INSIGHT software will be fully integrated into the SAS System.
This will allow the output to be displayed or used as
input to any SAS procedure.
CONCLUSION
The SAS System under UNIX operating systems and
derivatives has evolved into a powerful data processing tool. With the system-dependent features available in baseS AS software as well as the new products
to be available with Release 6.07, many functions
have been provided to take advantage of UNIX operating systems and derivatives.
References
Johnson, Bernadette(1989), "The SAS System under
UNIX and Derivative Operating Systems: New Features, New Power" in Proceedings of the Fowteenth
Annual SAS Users Group International Conference,
Cary, NC: SAS Institute Inc.
UNIX is a registered trademark of AT&T.
JMP, SAS, and SAS/GRAPH are registered trademarks and SAS/CONNECT and SAS/INSIGHT are
trademarks of SAS Institute Inc.
HP-UX is atrademark of Hewlett-Packard Company.
SunOS is a trademark of Sun Microsystems, Inc.
• change atuibutes of objects such as font,
color, size, and so on
ULTRIX is a uademark of Digital Equipment Cor-
• include other graphs into existing graphs.
AIX is a registered trademark of International Business Machines Corporation.
Using the Graphics Editor in combination with the
GIMPORT procedure provides the capability to
combine graphs from other software packages with
SAS/GRAPH OUipUL
poration.
00/UX is a uademark of Data General Corporation.
SAS/INSIGJ:ITTM is an additional new product that
will first be available with Release 6.07 on platforms
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