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Re: Print hello world not working

by Anonymous Monk
on Jul 15, 2020 at 08:00 UTC ( #11119351=note: print w/replies, xml ) Need Help??


in reply to Print hello world not working

What OS are computers using? I end shebang with space dash dash

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Re^2: Print hello world not working
by Marshall (Canon) on Jul 15, 2020 at 22:21 UTC
    I don't know why you would do that? That appears unnecessary to me. I guess that is like a null option. On Windows, the Perl path in the shebang line is ignored but options after that path like perhaps -w are parsed and used. I don't think a double dash followed by nothing means anything on any OS.
      -- is how you'd generally denote options for something else other than the first executable that's being called.

      For example for perl, perlrun says that: A -- signals the end of options and disables further option processing. Any arguments after the -- are treated as filenames and arguments..

      What this means roughly, IIRC, is that you use it to pass of options after -- to the perl script you're calling with perl.

      For example,

      $ perl -MSome::Module ./myperlscript.pl -- --my-opt1 foo --my-opt2 bar
      What this also means, I think, is that it's useless when part of the shebang line. Or maybe not, idk. Seems odd being in the shebang, though.

      Update - after thinking about it, I can see how this might be considered a defensive programming tactic. E.g., if somehow some script kiddie was seeking the add options to your shebang, having -- would make anything after moot. Similarly, adding __END__ at the end of your perl scripts would also neutralize someone blindly appending to your files.

        Interesting and new info for me, but does not seem useful in this context.
        I don't see why double dash would be used except perhaps for testing?
        Certainly I would not end the shebang line with a "proforma" double dash which has no purpose.

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