Without more to go on it is difficult to suggest much, but I think that you may be better served by the \b anchor than ^ and $.

From your snippit, it looks like you are concatenating several pieces of regex together before using them. This suggests that you could well end up with a regex that has several occurances of the ^ and $ anchors, which probably isn't what you want.

I'm also wondering why you are appending to $LookFor. If it is previously empty and you are using that as the pattern to match, that code should work. You probably don't want to append to it, just set it. Using qr// should help eliminate the escaping you've needed to do. And in that second regex, you can A) use \w which is a shortcut for the character class you've specified and B) eliminate the non-greedy matching as it doesn't help you because you've anchored your match anyway.

if ( $srch_host ) { 
    $LookFor = qr/^$srch_host$/;
} else { 
    $LookFor = qr/^\w+$/; 
}
[download]

-sauoq
"My two cents aren't worth a dime.";

1. $srch_host isn't being set or is mispelled. You probably need to add use strict; at the top of your script. That should catch a lot of spelling errors.
2. $LookFor is being concatenated to. That looks really weird, seeing as you're specifying the complete match with ^ and $. I would assign to $LookFor and go from there.

------
We are the carpenters and bricklayers of the Information Age.

The idea is a little like C++ templates, except not quite so brain-meltingly complicated. -- TheDamian, Exegesis 6

Please remember that I'm crufty and crochety. All opinions are purely mine and all code is untested, unless otherwise specified.

    if ($srch_file) {
        $LookFor .= "$^srch_file.*?";  
    }
        else {
        $LookFor .= '^[A-Za-z]+?';
    }

    if ($srch_year) {
        $LookFor .= "\.$srch_year";
    }
    else {
        $LookFor .= '\.\d+?';
    }

    if ($srch_month) {
        $LookFor .= "\.$srch_month";
    }
    else {
        $LookFor .= '\.\w+?';
    }

    if ($srch_host) {
        $LookFor .= "\.$srch_host"; 
    }
    else {
        $LookFor .= '\.\w+?'; 
    }

    print "Looking in:\n";  #look in the specified dir paths set in th
+e search_dirs
    foreach (@Search_Dirs) {
        print "\t$_/\n"; #print out dir paths that it searched
    }
    print "For file names matching: /$LookFor/\n"; #print out the file
+ names that matches
[download]

You appear to be printing out the final value of "$LookFor" as a confirmation/debugging message, prior to actually doing the search. So the big question is: what shows up as the value of "$LookFor"? Given the code and sample file names you've given us just now, the last bit we're missing is knowing the values of the various "$srch_XXX" strings -- maybe this can be guessed at if we know what shows up as the final value of "$LookFor", and it will be possible to work out why it's giving you results you don't want.

Apart from that, looking at what you have above, and assuming that "$srch_host" always has a literal-match string (like "box1", "box12", etc), then the part where you use "$LookFor" in a regex (not in your snippet) ought to work if you use it like this:

   if( /^$LookFor$/ ) {  # true if $_ contains a matching file name
      ...
   }
[download]

1. What is $LookFor and why are you appending to it?
2. In the second line, you escape the $... Update Thanks isotope, missed that they were double quotes... ; )

Please provide more of an explanation or more code.

Looks to me like $LookFor is a string to be used as the regular expression. In the second line, he's building it with the contents of $srch_host as an exact match, using double quotes, so for the ending anchor $ to be included literally he has to escape it. That said, I don't think he's included enough of the code to find where the problem lies.

--isotope