No need to use pastbin. You can add your code here just fine using code-tags (and readmore-tags)...

Some first comments:

use variable names which mean something, also to others :)

use consistent indentation in your code to improve readability

use lexical file and directory handles

this:

# Sorts files in $dir and sets $latest->{file} with newest file.
my $latest = (sort {$b->{mtime} <=> $a->{mtime}}
map {{mtime => -M $_, file => $_}}
<$dir/*>)[-1];
my $newM = (stat $latest->{file})[9];
 
# Sorts files in $dir and sets $oldest->{file} with oldest file.
my $oldest = (sort {$a->{mtime} <=> $b->{mtime}}
map {{mtime => -M $_, file => $_}}
<$dir/*>)[-1];
my $oldM = (stat $oldest->{file})[9];
[download]

to determine the oldest and newest file, could easier be writen as:

my ($newM, $oldM) = (sort {-M $a <=> -M $b} <./*>)[0,-1];
[download]

No need for maps etc. (oh, and better use glob...)

HTH,