can I print the result to a file and not on the display only?

Did you even try to figure this out by yourself or are you just looking for someone to do all your work for you?

https://perldoc.perl.org/functions/select.html
select FILEHANDLE

If FILEHANDLE is supplied, sets the new current default filehandle for output. ... , a write or a print without a filehandle default to this FILEHANDLE.

In reply to Re^3: Merge the difference between two files by huck
in thread Merge the difference between two files by hopper

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