• Why are you using a hash to store what seems like a simple list of file names? I would use a simple @array.
• Searching directories/subdirectories is best done by a module like File::Find.
• use the perl grep function to search an array.
• use the perl rename function to move files.

Why are you using a hash to store what seems like a simple list of file names? I would use a simple @array.

use the perl grep function to search an array.

Don't you see the contradiction in these two sentences? I'd use a hash, but with the names read into the keys, not the values. That way, you can easily check whether a filename is in the hash. For example,

while(<>) { /(.*)/; $names{$1} = 1; } 
use File::Find (); 
File::Find::find sub { 
    $names{$_} and -x and print $File::Find::name, "\n"; 
    }, grep -e, split ":", $ENV{"PATH"};
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searches for binaries with the names given on ARGV.

Clever code!

I would have used chomp instead of "/(.*)/", and split on ";" for Windoze.

Anyway, to respond to your question - I had not optimized my proposed solution to the extent you have, so I did not see the "contradiction". My proposal suggested storing the file names in an array, and "grep"ping it for each file.

I would agree that your solution is faster. To optimize memory it even more, you could set "$names{$1}=undef", and use "exists $names{$_}" when querying.

    ..."I don't know what the facts are but somebody's certainly going to sit down with him and find out what he knows that they may not know, and make sure he knows what they know that he may not know, and that's a good thing. I think it's a very constructive exchange," --Donald Rumsfeld

#!/usr/bin/perl
use Cwd;

open(FILE, "<dup01032004.txt");

while (<FILE>) {

$hash{$.} = $_;

}

close(FILE);

foreach (keys %hash) {
        my ($num) = $hash{$_} =~ m/(.*)?\..*/;
        if (-d $num) {
                # ah! the folder exists!
                print("The folder $num exists! so make your killerapp
                       do the work!!!\n");
                chdir $num or die("Cannot change to directory\n");
                print "Current folder = " . getcwd() . "\n";

                #Now do your stuff in this folder here!

                chdir ".." or die("Cannot go back...\n");
                print "Current folder = " . getcwd() . "\n";
        }

}
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Dave.