Environment Variables are an old unix feature to let users customize their environment in different ways. Essentially they're a shell feature for sharing information between applications. For example, there's an EDITOR environment variable that you can set to "emacs" or "vi" (or "pico" or whatever), and any app that wants to give you the ability to edit some text is supposed to check EDITOR to find out which editor to kick you into.

In the example you quoted, the idea is instead of having a $VERBOSE global inside of your perl code, you've got an even more global VERBOSE environment variable so that different processes can see if you're in a chatty mood or not.

The "//" is a newish perl feature, it's a variant of "||". The idea is that the code looks for the VERBOSE environment variable to get the $Verbose setting, but if it can't find that envar, it'll default to 1 instead. "//" is defined-or, so it checks to see if it's defined, rather than checking to see that it's true, so that a setting of "0" will be passed through.

In reply to Re: Environment variables by doom
in thread Environment variables by neutron

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