It says cannot do inplace edit without backup at line 9
If you get an error message you don't understand, use diagnostics can offer extra explanation, or you can just look the error up in perldiag

In this case, you would have read: 

Can't do inplace edit without backup
  (F) You're on a system such as MS-DOS that gets confused
  if you try reading from a deleted (but still opened) 
  file.  You have to say "-i.bak", or some such.

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In reply to Re: in place edit - how to do by FunkyMonk
in thread in place edit - how to do by smanicka

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