#!/usr/bin/perl
use strict;
use warnings;

# 3 argument form of open using a lexical variable is considered better practice
# see perldoc -f open
open my $file, '<', $ARGV[0] or die "Can't open $ARGV[0] for reading: $!\n";

while (my $line = <$file>) {
  print $line;
  chomp($line);   #if you need to
  
  # any other processing....
}