Perl Explained: The Duct Tape That Held the Internet Together

Before Python was the default scripting language, there was Perl. Released in 1987, it powered the early dynamic web, system administration, and bioinformatics - and its motto, "there's more than one way to do it," made it the most expressive, and most notorious, language of its era.

Perl is still running critical systems today, and its greatest gift to programming is one you use daily without thinking: regular expressions, which Perl made a first-class language feature.

Text processing, regex, and CPAN

Perl's model rests on a few distinctive ideas:

• Text first - strings, files, and reports are Perl's home turf: slurp a file, transform it, print a report, in a handful of lines.
• Regular expressions built in - pattern matching is not a library but syntax: =~ applies a regex directly, and Perl's regex engine set the standard others copied.
• Context sensitivity - the same expression behaves differently in scalar and list context, which makes short scripts very short - and long programs harder to read.
• CPAN - the Comprehensive Perl Archive Network, the original giant package repository, with a module for nearly everything, decades before npm or PyPI.

A tiny example shows the shape - read lines, keep the matching ones, print them transformed:

#!/usr/bin/perl
use strict;
use warnings;
while (my $line = <>) {
  if ($line =~ /error/i) {
    print uc $line;
  }
}

Feed it a log file and it prints every error line in uppercase: pattern matching, file handling, and transformation in six lines. That density is Perl's whole appeal - and, critics say, its whole problem.

The honest trade

Perl's trade is readability and fashion: dense, symbol-heavy code can be hard to read months later ("write-only" is the joke), and new projects rarely choose Perl over Python.

The rule of thumb: Perl when maintaining or extending existing Perl systems, or for quick text-processing scripts; Python when starting fresh or working in a team that must read the code later.

Takeaway

Perl is the duct tape that held the internet together: text processing, built-in regex, and CPAN, in a language optimised for getting the job done fast. It trades readability for expressive density - and for the systems it still runs, that trade was worth making.

Originally published at https://practicaldevblog.blogspot.com/2026/10/perl-explained-duct-tape-that-held.html