in reply to perl functionality like unix's "sort -u" and "uniq -c"

sort -u is pretty much 
my %hash = map {($_ => undef)} <>;
print sort keys %hash;

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and uniq -c is pretty much 
my $prev=<>;
my $count=1;
while (<>) {
   if ($prev eq $_) { $count++ }
   else {
       printf "%4d %s", $count, $prev;
       $count = 1;
       $prev = $_;
   }
}
printf "%4d %s", $count, $prev;

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More complete implementations of Unix tools in Perl are available from CPAN as PPT::Util.
Caution: Contents may have been coded under pressure.

In Section Seekers of Perl Wisdom