In Perl, you have a variety of special variables available to you ... preloaded with information in many cases. Some of their names are "special" such as $^O, $^T, $", $/, $! or $_, and others are capitalised such as @ARGV, @ISA, %INC and %ENV.

Here's a snippet of code that checks whether you're running on a Microsoft based operating system through the $^O variable, then splits the PATH environment variable which it gets from the %ENV hash into a series of directories that the operating system searches for executable programs.

$sep = ($^O =~ /^MS/) ? ";" : ":"; # Windows uses ; separator
@pels = split(/$sep/,$ENV{PATH});


The complete code example, which lists out all executable files available to you in alphabetic order, is listed here.
(written 2008-07-10 06:42:35)

 P210 - Perl - Topicalization and Special Variables

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