Some Perl idioms

Recently I have worked with Perl again for some system monitoring scripts. Some people at Lunatech, where I work, are real Perl mavens. Here are some quick reminders

Constants

use constant CONSTANT_NAME => "constant value"; creates a compile time constant. It is mainly useful for clarifying intent, although if the right side is a more complex expression, for instance a calculation, there might be some performance benefit. Learn more about constants in the official Perl docs.

Regular expressions

1. my @matches = my $variable =~ <regex> if there is a match, @matches will contain the values of the capture groups in the regular expression.

2. my $string =~ s/<pattern>/<replacement>/ if any substitutions have been made, in addition to modifying $string, will evaluate to true. Handy for use in conditionals.