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PERL - What is it?

Perl is a language optimized for scanning arbitrary text files, extracting information from those text files, and printing reports based on that information. It's also a good language for many system management tasks. The language is intended to be practical (easy to use, efficient, complete) rather than beautiful (tiny, elegant, minimal).

Perl combines (in the author's opinion, anyway) some of the best features of C, sed, awk, and sh, so people familiar with those languages should have little difficulty with it. (Language historians will also note some vestiges of csh, Pascal, and even BASIC-PLUS). Expression syntax corresponds closely to C expression syntax. Unlike most Unix utilities, Perl does not arbitrarily limit the size of your data--if you've got the memory, Perl can slurp in your whole file as a single string. Recursion is of unlimited depth. And the tables used by hashes (sometimes called "associative arrays") grow as necessary to prevent degraded performance. Perl can use sophisticated pattern matching techniques to scan large amounts of data quickly. Although optimized for scanning text, Perl can also deal with binary data, and can make dbm files look like hashes. Setuid Perl scripts are safer than C programs through a dataflow tracing mechanism that prevents many stupid security holes.

If you have a problem that would ordinarily use sed or awk or sh, but it exceeds their capabilities or must run a little faster, and you don't want to write the silly thing in C, then Perl may be for you. There are also translators to turn your sed and awk scripts into Perl scripts.

But wait, there's more...

Perl version 5 is nearly a complete rewrite that provides the following additional benefits:

·         modularity and reusability using innumerable modules
·         embeddable and extensible
·         roll-your-own magic variables (including multiple simultaneous DBM implementations)
·         subroutines can now be overridden, autoloaded, and prototyped
·         arbitrarily nested data structures and anonymous functions
·         object-oriented programming
·         compilability into C code or Perl bytecode
·         support for light-weight processes (threads)
·         support for internationalization, localization, and Unicode
·         lexical scoping
·         regular expression enhancements
·         enhanced debugger and interactive Perl environment, with integrated editor support
·         POSIX 1003.1 compliant library


Stuff

Making graphs with Perl and GNUPlot


Links

Rex Swain's HTMLified Perl 5 Reference Guide

 

Sun, 30 September, 2001 17:54 Previous PageNext Page

 
 
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© 2001-2003, Yee-Ting Li, email: ytl@hep.ucl.ac.uk, Tel: +44 (0) 20 7679 1376, Fax: +44 (0) 20 7679 7145
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