Doesn't <> within the while loop open the files the users enters in the command line?

Yes, and there's more to it. Read about the null filehandle in I/O Operators, there's much to learn about @ARGV, $ARGV and ARGV, all three being "magical".

perl -le'print map{pack c,($-++?1:13)+ord}split//,ESEL'

In reply to Re^7: reading files to different output files. by shmem
in thread reading files to different output files. by ic23oluk

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