Warning about the above for the future reader:

Both regexen were originally written without the /i. Then (belatedly) recognition of the need for case insensitivity on the file extension set in. /me (insufficient thought) just added /i... without fixing the rest of the regexen.

Duh. That kind of thoughtlessness during late-night (or early morning) code revision has bit me before. Perhaps this will warn others.

The regexen don't need the a-z when the i is added. Obvious? Yes, but not at the (befuddled) time.

And the second version would be better and more clearly written with a negated match:  if ($item !~/^[A-Z0-9]+\.jpg$/i) {

Tested:

#!/usr/bin/perl
use strict;
use warnings;
# 839761

my @foo=("a.jpg", "b.txt", "Cde.jpg", "abc.jpg.delete_everything.exe",
+ "123.jpg", "|#&.exe");
print "Using negative match, '!~'- items which match should be exclude
+d:\n\n";

for my $item(@foo) { 
    if ($item !~/^[A-Z0-9]+\.jpg$/i) {
        print "\t--> (negated) match: $item \n";
    }else{
    print "no match in \$item: $item \n";
    }
}
print "\n\n". 'Now using /^[A-Z0-9]+\..+$/i' . " so matched should be 
+accepted: \n\n";
for my $item(@foo) { 
    if ($item =~/^[A-Z0-9]+\.jpg$/i) {
        print "\t --> match: $item \n";
    }else{
    print "no match in \$item: $item \n";
    }
}
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