Piercer, I could not get your script to fail, but we seem to be using different versions of nbtstat.

I looked at your requirements, and although all the suggestions are good ones, it appears I might have something to offer in trying to satisfy all the requirements.

• get the first 15 characters of each line
• no duplicates
• in comma delimited form.

#!c:\perl\bin\perl -w
use strict;

# open(NB, "nbt.csv")|| die"Cant open input file nbt.csv";

# NBT.CSV simply contains ip addresses - one per line
# as DATA sample does

my %stathash = ();

while(my $ip = <DATA>){
    chomp $ip;
    
    #put nbtstat results in an array, one line = one element
    my @nbtstat    = split /\n/, `nbtstat -a $ip`;

    #modify @nbtstat to discard gibberish (if desired)
    for (@nbtstat){
          s/^\s+//g;
          $_       = substr($_,0,15);
          s/[^a-z|A-Z|_|0-9|\040]//g;
          s/\s+$//g;
    }
    # remove duplicates from array
    my %uniq;
    @nbtstat       = grep { ! $uniq{$_} ++ } @nbtstat;

    $stathash{$ip} = \@nbtstat;
}

for my $key (keys %stathash){

  print "\n$key: \n";

  #skip empty elements otherwise print to list
  /.+/ and print "$_," for @{$stathash{$key}};
} 

__DATA__
192.168.0.2
192.168.0.4
192.168.0.5
192.168.0.6
[download]

Result:
192.168.0.2:
Local Area Conn,Node IpAddress,Host not found,
192.168.0.4:
Local Area Conn,Node IpAddress,NetBIOS Remote,Name,OWL,TISIMAGING,MAC Address,
192.168.0.5:
Local Area Conn,Node IpAddress,NetBIOS Remote,Name,DELTA,TISIMAGING,MAC Address,
192.168.0.6:
Local Area Conn,Node IpAddress,NetBIOS Remote,Name,PANAMA,TISIMAGING,MAC Address,

mkmcconn