Are you asking how to read the file a line at a time?

my $file_name = ...;

open(my $fh, '<', $file_name)
   or die("Unable to open file \"$file_name\": $!\n");

while (<$fh>) {
   # $_ contains a line, including the "\n".
   # Use "chomp;" to remove the trailing "\n".
   ...
}
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By the way, please use <c>...</c> instead of <pre>...</pre> on PerlMonks.