Unformatted text preview: "used in a variety of contexts. For an individual run of such an application,
programmers must configure a setup to customize the application for its current
run. This setup can be specified in the form of a script written in a scripting
language. The script integrates individual commands into a single command that
can be used to drive application execution.
A scripting language is interpreted, rather than compiled. Hence a script can
interact with a running program and change during the run. In addition to
controlling a running program, scripts can preprocess and post process data.
Scripting languages typically let programmers invoke individual application
components directly. Application components are individual programs, such as
data format converters and visualizers that carry out specific data processing tasks
and can be used in different contexts
Some commonly known scripting languages are Unix Shell Script, Perl, Tel, and
Python. A typical script looks like the one shown in Figure 12.27.
users = 'who I we —1'
if test $users -gt 10
then echo "More than 10 users logged on"
Figure 12.27. A typical script. The first line of the script sets the variable 'users'
equal to the value produced by the pipeline of commands 'who I we -F. This is in
fact a count of the number of users currently logged on to the system. This value is
then compared with the number 10, and if it is greater, then the message is
Fourth-Generation Languages (4GLs)
Some people in the computer field like to identify the major developments in
programming language area by generations. According to them, machine
languages, assembly languages, and high-level languages are identified as firstgeneration, second-generation, and third-generation languages respectively. Every
new generation of language brought significant improvement in programmer
productivity by making programming languages more and more user-friendly.
Studies indicate that the move from first-generation machine langua...
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This document was uploaded on 04/07/2014.
- Spring '14