To avoid redundancy in your code, you could do this: 
my %seen;

while (<>)
{
     next if ($seen{$_}++);
     print;
}

[download]
You can do it in one shot, so you might as well. Note that this code eliminates all duplicate lines, not just repeated ones. If you want to just ditch repeats, use this: 
my $last;

while (<>)
{
     next if ($_ eq $last);
     $last = $_;
     print;
}

[download]
Thus lines "A A A B B B A A C C" will be "A B A C" not "A B C" as in the previous bit.

In reply to Re^2: to avoid redundacy in a file by tadman
in thread to avoid redundacy in a file by Anonymous Monk

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