If you run the script on Unix ($/ = "\n"), but the files are saved on Windows ($/ = "\r\n"), you'll get botched result. Don't trust chomp, use s/\s*$//s instead. Or better yet, use regexp matching and capturing (this is what -T mode and perlsec would suggest):

while (<SYM>) {
    m/($insert_expected_symbol_format_here)/ 
        or die "Bad input format"; # or maybe just "or next"
    my $symbol = $1;
};
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