Introduction to Perl

1.1 What is Perl?

Perl ("Practical Extraction and Report Language", a backronym) was created by Larry Wall in 1987. It's a high-level, general-purpose, interpreted, dynamic language.

It's famous for text processing and regular expressions, and was the "duct tape of the Internet" in the CGI era. Its motto is TMTOWTDI ("There's More Than One Way To Do It").

Perl 5 is the actively developed language (yearly releases: 5.36 in 2022, 5.38 in 2023, 5.40 in 2024, 5.42 in 2025). Raku (formerly "Perl 6") is a separate sister language.

1.2 Key Features

Perl-compatible regex (PCRE was modeled on Perl) built into the syntax Sigils and context

$scalar, @array, %hash; expressions behave differently in scalar vs list context

Values convert automatically between strings and numbers Hundreds of built-in functions for text, files, processes, and networking

The Comprehensive Perl Archive Network: 200,000+ modules Procedural, object-oriented, functional

Runs on Unix/Linux, macOS, Windows, and many more systems; preinstalled on most Unix systems Decades-old scripts generally still run

Among the most thorough Unicode support of any language

1.3 Where Perl Is Used

System administration and DevOps: log parsing, automation, monitoring (Nagios plugins), configuration management glue.

Text and data processing: ETL, report generation, data munging.

Bioinformatics: BioPerl, sequence analysis pipelines.

Web: Mojolicious, Dancer2, Catalyst; legacy CGI. Sites such as Booking.com, DuckDuckGo (historically), cPanel, IMDb (historically), and Craigslist rely on Perl.

Testing: Perl's TAP (Test Anything Protocol) influenced testing in many languages.

Finance, telecom, network engineering, and maintaining large legacy codebases.

1.4 Perl vs Other Scripting Languages

Dynamic, context-sensitive Built into the syntax Limited (=~ in [[ ]]) "One obvious way" Excellent (-n -p -i -a -e)