#! perl -slw
use strict;

my $dir = $ARGV[ 0 ] || die 'Need a directory';

my %hash;
while( my $file = <"$dir/*.log"> ) {
    open my $fh, '<', $file or die "$file : $!";
    while( <$fh> ) {
        $hash{ $_ } = 1;
    }
    close $fh;
}

open my $fh, '>', "$dir/composite.log" or die $!;
print $fh $_ for sort keys %hash;
close $fh;