Perl Tutorial-Basics
Venkat Thirumala
Why Perl
Perl is built around regular expressions
REs are good for string processing
Therefore Perl is a good scripting language
Perl is especially popular for CGI scripts
Perl makes full use of the power of UNIX
Short Perl programs can be very short
"Perl is designed to make the easy jobs easy, without making the difficult jobs impossible." -- Larry Wall, Programming Perl
Why not Perl
Perl is very UNIX-oriented
Perl is available on other platforms...
...but isn't always fully implemented there
However, Perl is often the best way to get some UNIX capabilities on less capable platforms
Perl does not scale well to large programs
Weak subroutines, heavy use of global variables
Perl's syntax is not particularly appealing
What is a scripting language
Operating systems can do many things
copy, move, create, delete, compare files
execute programs, including compilers
schedule activities, monitor processes, etc.
A command-line interface gives you access to these functions, but only one at a time
A scripting language is a "wrapper" language that integrates OS functions
Major scripting languages
UNIX has sh, Perl
Macintosh has AppleScript, Frontier
Windows has no major scripting languages
probably due to the weaknesses of DOS
Generic scripting languages include:
Perl (most popular)
Tcl (easiest for beginners)
Python (new, Java-like, best for large programs)
Perl Example 1
#!/usr/local/bin/perl
#
# Program to do the obvious
#
print 'Hello world.'; # Print a message
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