in reply to Count of patterns in a file without knowing pattern in advance

This is a FAQ. 
my %seen;
while (<$FILE>) {
    chomp;
    ++$seen{$_};
}

for my $string (keys %seen) {
    print "$string encountered $seen{$string} time(s).\n";
}

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map{substr$_->[0],$_->[1]||0,1}[\*||{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^*ARGV,3]

In Section Seekers of Perl Wisdom