in reply to use of << on comand line

That's the Heredoc syntax (as interpreted by your shell in thiscase, not perl). It simply writes the data to the standard input so you can read it with <STDIN> (the magical <> will try to use the parameters as the name of files to read from, unless you shift from @ARGV).

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Re^2: use of << on comand line
by cweeble (Novice) on Jun 04, 2018 at 14:51 UTC
    Thanks Eily. It works now :) I'll have to remember to watch out for that magical <> feature you mentioned. I never realised it works like that... Fortunately I usually shift parameters from @ARGV.

      You can find the documentation for the feature in perlop (search for "The null filehandle"). And you'll find more info on the problems of the magical <> and a safer version here