Perl
Overview
Introduction
Why yet
another utility?
Beginning
Perl
Invoking Perl
Documentation on
perl
Perl Scripts
Variables
Input
and output
Files and
redirection
Pipes
The DATA
filehandle
Fields
Control structures
Predefined Perl
Functions
Modules
Regular expressions
Single
character translation
String
editing
Perl and the Kernel
Quality
code
When do I use Perl?
Summary
Exercises
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When do I use Perl?
Use Perl whenever you want. Anything you can program in the
shell can be done in Perl. It is up to you to decide when the extra
complication of using Perl actually saves you time. If you want to
view the first line of a file, use head. It's easy,
and a Perl program would be overkill. However, if you cannot
identify simple UNIX utilities to perform the task you need done,
then think about Perl. Complicated shell programming gets messy,
and Perl is more suitable for non-trivial tasks.
There is one other reason to use Perl - security.
Suppose you write a command to be used and owned by
root, and to be accessible by a general user. An
example might be a program for sending email, which requires write
access to system files (including log files). It is
dangerous to write such a program as a shell script, since
under certain circumstances a user can use their knowledge of the
shell environment to gain a subshell with root privileges. This can
be prevented if the program is written in Perl.
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