Cut 'n paste from perlman:perldiag (consult your own system's documentation with perldoc perldiag or place use diagnostics at the top of your script for a more definitive answer)

Can't ignore signal CHLD, forcing to default
(W signal) Perl has detected that it is being run with the SIGCHLD signal (sometimes known as SIGCLD) disabled. Since disabling this signal will interfere with proper determination of exit status of child processes, Perl has reset the signal to its default value. This situation typically indicates that the parent program under which Perl may be running (e.g. cron) is being very careless.

So, I suppose, in a way, the answer is "yes, there are sometimes issues between cron and perl," and you seem to have run across one of them.

How to fix it? One way is to make it explicit at the beginning of your script, using the special block BEGIN:

#!/usr/bin/perl -w

use strict;

BEGIN {
    SIG{CHLD} = 'DEFAULT';
}
[download]

As an aside, I'd suggest going all-perl with this project,

• fetch the pages with LWP::Simple
• print fetched page to a file
• compare the new file to one you've created earlier using this same process
• you can use File::Compare for the file comparison

Philosophy can be made out of anything. Or less -- Jerry A. Fodor