Editor: emacs

Emacs is a very full-featured editor available for pretty much every operating system. Your installation should highlight Perl code correctly if you save your file with a .pl extension.

Emacs ships with two modes for Perl editing: a simple perl-mode and a more advanced cperl-mode. You should probably use cperl-mode unless you have a special reason not to; to do so, add (defalias 'perl-mode 'cperl-mode) to ~/.emacs. To indent using four spaces per level, add (setq-default indent-tabs-mode nil) and (setq cperl-indent-level 4) to your .emacs.