2. INTRODUCTION TO SCRIPTS AND SCRIPTING
Script is a program written for special runtime environment that automate the
execution of tasks.
Scripting is the action of writing scripts using scripting language.
Scripting Language are used to extend the functionality of software . For
example enhancing web pages by providing dynamic content.
They are designed to automate frequently used task that usually involve calling
or passing commands to external program.
Examples:
1. PERL- PRACTICAL EXTRACTION AND REPORT LANGUAGE
2. PHP-Hypertext Preprocessor(Personal Home Page)
3. TCL-Tool Command Language and PYTHON
TCL
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3. SCRIPTING VS. PROGRAMMING: IS THERE A
DIFFERENCE?
Scripting Programming
Scripts are interpreted . It means
they are processed from scratch
every time you run them.
Programs are executed.
Problems addressed by Scripting language
Building applications from off-the-shelf components.
Example:
Use of Visual Basic to develop GUI using prebuilt Visual Controls.
Controlling applications that have a programmable interface(protocols
to be followed while building a software).
Speed of development is more important than runtime efficiency.
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4. ORIGIN OF SCRIPTING
The UNIX O.S developers coined the term shellscript for sequence of commands that
were read from a file and followed in sequence.
Script is a file that is intended to be executed directly rather than being compiled.
Examples of scripts with respect to unix system are:
AWK: This utility reads the standard input line by line and takes an action on part of
entire line.
These actions are specified in awk script that consist of list of instructions.
Perl: is a scripting language developed by Larry Wall, especially designed for text
processing.
Though Perl is not officially an acronym but many times it is used as it stands
for Practical Extraction and Report Language.
It runs on a variety of platforms, such as Windows, Mac OS, and the various versions
of UNIX.
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5. ORIGIN OF SCRIPTING
In DOS(Disk Operating System), use of dial up connection to remote system
require scripts that automate the sequence of operation required to establish a
connection to remote system.
Use rasphone( Remote Access Phonebook) command.
Another occurrence of script was in Apple Macintosh HyperCard Application,
which is one of the Hypertext system.
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6. SCRIPTING TODAY
Scripting allows application to be developed much faster than traditional
methods allow.
We can use it to manipulate,customize,automate the facilities of existing
system.
Eg: Use of client side scripting and Dynamic HTML to create interactive and
feature rich enhanced web pages.
Using Scripting Language with its rich functionality .These are used by UNIX
admin for System maintenance work, like managing user permissions.
Windows system admin adopt Perl for their work.
Apache web server has an embedded Perl interpreter for CGI scripts
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7. CGI SCRIPT ISAPI TECHNOLOGY
CGI stands for Common Gateway
Interface.
It defines a standard way in which
information may be passed to and
from the browser and server.
CGI scripts can be written using
PERL.
ISAPI stands for Internet Server
Application Program Interface
technology . It is set of window program
calls that let you write a web server
application that will run faster than CGI.
We can create Dynamic Link Library
application file using this technology.
We can write an ISAPI script in any
language that will create an executable
object on your system. For example, C++,
Visual Basic, or Perl script on Windows.
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