A perl script which finds strings which are in the $checkStrFile($ARGV[0]) but not in the $targetFile($ARGV[1]).

findNonExistStr.pl

use strict;
use warnings;

my $checkStrFile = $ARGV[0];
my $targetFile = $ARGV[1];

open(my $csFh, "< $checkStrFile") or die "Can't open $checkStrFile: $!";
open(my $tgtFh, "< $targetFile")  or die "Can't open $targetFile: $!";

while (my $checkLine = <$csFh>) {
    next if ($checkLine =~/^#/);
    chomp($checkLine);
    
    my $found = 0;
    while (my $tgtLine = <$tgtFh>) {
        next if ($tgtLine =~/^#/);
        
        # I should't use regular expressions here.
        my $checkLineQuoted = quotemeta($checkLine);
        
        # If $tgtLine has a pattern of $checkLineQuoted.
        if ($tgtLine =~/$checkLineQuoted/) {
            $found = 1;
            last;
        }
    }
    # Perl keeps a position of $tgtFh, so it is necessary to seek it to the beginning of the file.
    seek($tgtFh, 0, 0);
    
    if ($found == 0) {
        print "$checkLine\n";
    }
}

close($csFh);
close($tgtFh);