perldoc -f -x

-p File is a named pipe (FIFO), or Filehandle is a pipe. 

 if( -p STDIN ){ @stuff = <STDIN>; close STDIN; }
while(<>){ ...

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See Re^2: Write to existing file with character insert and Iterator::Diamond for a safer way

In reply to Re: How to handle both a STDIN pipe and file from command line? by Anonymous Monk
in thread How to handle both a STDIN pipe and file from command line? by keithw99

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