I have a comma seperated file, and wish to remove duplicate lines based on column b,c & d, but keeping the one with the lower value letter ( in my case F not S ) from column E. 
input
1,ken,james,smith,s
11,ken,james,smith,f
0,ken,james,smith,s

output
11,ken,james,smith,f

[download]
seek $ifh, 0, 0;


my @file = <$ifh>;

my @array;
my %hash;
foreach my $_ (reverse @file) {


    chomp;
    next
        if  ! m/^\s+\d/;
    s/^\s+//g;
    s/\s+$//g;
    s/\s+/,/g;

    my $key = join ',', ( split /,/ )[ 1, 2, 3 ]; # remove duplicates 
+column b,c,d
   #push @array, $_
    
     print  $_, "\n"
        if  ! $hash{$key}++;
}

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In reply to perl to remove duplacate based on columnb,d & by john.tm

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