Compared with file I/O manipulating hashes is cheap. Something like this perhaps:

use warnings;
use strict;

open inFile, '<', "accts_to_exclude.txt" || die "Cannot open accts_to_
+exclude.txt";
my %excludeList = map {chomp; $_ => undef} <inFile>;
close inFile;

open inFile, '<', "list1.txt" || die "Cannot open list1.txt";
my %acctList = map {chomp; $_ => undef} <inFile>;
close inFile;

open inFile, '<', "list2.txt" || die "Cannot open list2.txt";
my %diffList = map {chomp; $_ => undef} <inFile>;
close inFile;

open inFile, '<', "list3.txt" || die "Cannot open list3.txt";
my %nameList = map {chomp; $_ => undef} <inFile>;
close inFile;

open orgAcctList, '<', "orig_accts.txt" || die "Cannot open orig_accts
+.txt";
open outFile, '>', 'output.txt' || die "Cannot open output file output
+.txt";

while (my $line = <orgAcctList>){
    chomp $line;
    my ($filename, $state, $amt, $ttl, $account, $name, $invnum) = spl
+it /\t/, $line;
    next if exists $excludeList{$account};
    print outFile "$filename $state $amt $ttl $account $name $invnum\n
+";
    
    if (defined $acctList{$account}) {
        # do something (write this info to file1)
        next;
    }
    
    if (defined $diffList{$account}) {
        # do something (write this info to file2¡K)
        next;
    }
    
    if (defined $nameList{$name}) {
        # do something (write this info to file2)
        last;
    }
}
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Thank you both for your response. Graff, your tool is indeed very helpful for a lot of what we do. For this solution though, Grandfather's solution does seem a bit more relevant and as I am somewhat under time constraints to complete this script, it seemed more logical as I can add on to my existing code.
I've made some slight changes to the code above ...but after spending numerous hours debugging the script, I still can't seem to get it work properly. I maybe missing some logic here...but when I run the script, it seems to output everything into nc_load.txt

Here's the code:


#!/usr/bin/perl -w
$excludeaccts = "accts_to_exclude.txt";
open(EXCLUDELIST, $excludeaccts) || die ("Cannot open $excludeaccts");
#Load accounts-to-exclude into a hash table
%exclusionlist = map {chomp; $_ => undef} <EXCLUDELIST>;
close(EXCLUDELIST);

$ncaccts = "nc_acct_list.txt";
open(NCLIST, $ncaccts) || die ("Cannot open $ncaccts");
%ncacctlist =  map {chomp; $_ => undef} <NCLIST>;
close(NCLIST);

$ccaccts = "cc_acct_list.txt";
open(CCLIST, $ccaccts) || die ("Cannot open $ccaccts");
%ccacctlist = map {chomp; $_ => undef} <CCLIST>;
close(CCLIST);

$ccnames = "cc_name_list.txt";
open(CCNALIST, $ccnames) || die ("Cannot open $ccnames");
%ccnamelist = map {chomp; $_ => undef} <CCNALIST>;
close(CCNALIST);

$origaccts = "orig_accts_list.out";
open(ORIGACCTLIST, $origaccts) || die ("Cannot open $origaccts");

open($output, '>', 'output.txt' || die "Cannot open output file output
+.txt");

open($ncoutput, '>','nc_load.txt' || "Cannot open output file nc_load.
+txt");
open($ccoutput, '>', 'cc_load.txt' || "Cannot open output file cc_load
+.txt");

while ($line = <ORIGACCTLIST>){
chomp $line;
($filename, $state, $amt, $ttl, $account, $name, $invnum) = split /\t/
+, $line;
next if exists $exclusionlist{$account};
print $output "$filename\t$state\t$amt\t$ttl\t$account\t$name\t$invnum
+\n";


if (defined $ncacctlist{$account}) {
        print $ncoutput "$filename\n";
        next;
    }

if (defined $ccacctlist{$account}) {
        print $ccoutput "$filename\n";
        next;
    }

if (defined $ccnamelist{$name}) {
        print $ccoutput "$filename\n";
        last;
    }
        print $ncoutput "$filename\n";
###(I added the above line such that anything that's not in $nccctlist
+, $ccacctlist, $ccnamelist will be printed to nc_load.txt file If I r
+un it without this line, nothing is being printed to nc_load.txt or c
+c_load.txt)###
}
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Any suggestions as to what I maybe doing wrong here? Thanks.

I see you are using if (defined $xxx{$yyy}) where you probably intended if (exists $xxx{$yyy})

In general it is useful to provide the fail reason for opens using $!:

open(NCLIST, $ncaccts) || die ("Cannot open $ncaccts: $!");
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The line open($output, '>', 'output.txt' || die "Cannot open output file output.txt"); has a missing ) and (. It should be open($output, '>', 'output.txt') || die ("Cannot open output file output.txt: $!");

You should always use the three parameter open. It makes the input explicit and in other contexts where the file name is provided by the user avoids malicious effects from a user putting > at the start of a file name.

---

DWIM is Perl's answer to Gödel

Update: Grandfather's code is of course more relevant for you, and neater, because it does a bunch of files in one swoop. My own tool just compares two lists at a time (like "diff" or "cmp"), but for many cases, you can just chain runs together through a pipe -- e.g. print rows in file1 whose initial field does not match any rows in file2 or file3, and do match rows in file4:

cmpcol -x1 -l1 file1 file2 | cmpcol -x1 -l1 stdin file3 | cmpcol -i -l
+1 stdin file4
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