Perl is complaining because certain variables in your Darwin environment aren't set in a way that matches what Perl expects.

As the other poster correctly guessed, OS X uses a csh variant (tcsh IIRC) by default, so if you haven't changed shells (you would know if you had installed bash, for example), that's what you're using.

Look in your home directory (hit the little house button in Finder, or cd ~ in Terminal then ls .*) for a file with a name that starts with a period and has csh in its name, like .cshrc or .tcshrc (I can't check right now the exact name, because the OS X system I have access to seems to be not responding at the moment; probably my boss isn't in right now so her iMac is asleep).

Open that file up in your text editor. (I forget what they renamed the OS X version of SimpleText, but it's got the word "Text" in the name and is in your Applications folder.) Here you can make changes, save them, and then next time you open Terminal they should be in effect. It is a good idea to make a backup copy of the file first.

The set commands that the other poster gave you will probably do approximately what you want; if not, open Terminal and try man csh or man tcsh and it should have some (somewhat technical) information about how your shell works. Type /environment and hit enter to scan forward to the section on setting environment variables. (You may have to scan forward several times to find the relevant section.) I can't get any more detailed than that, because I normally use bash, which does things a bit differently from csh (or eshell, which does things a lot differently from both, or DCL, which is even more different from all of the above, or COMMAND.COM which is its own thing too). My knowledge of csh is quite limited.

 --jonadab