On the HTML side you will need a form and submit button to run the update script.

<form method="POST" action="http://somesite.com/cgi-bin/script.pl">
<input type="Submit" value="Update">
</form>

# for the script
#!/usr/bin/perl -w

use CGI;
use Fcntl qw(O_WRONLY O_CREAT O_EXCL);
my $q = new CGI;
my $lockfile = '/tmp/lock';
if (sysopen(FH, $lockfile, O_WRONLY | O_CREAT | O_EXCL)) {
    # sysopen will only work if lockfile does not exist
    # exec the script and wait for it to complete using bacticks or ex
+ec
    `your_update_script`;
    close FH;
    unlink $lockfile or error("<h3>Can't unlink lockfile $lockfile $!<
+h3>");
    print $q->redirect('http://page_to_display_after_update');
}
else {
    error("<h3>Update already in progress!</h3>");
  exit;
}

sub error { print $q->header, shift; }
[download]

Note that there will be collisions with your cron job unless you write a similar short lockfile script and exec that from cron like:

#!/usr/bin/perl -w

use Fcntl qw(O_WRONLY O_CREAT O_EXCL);
my $lockfile = '/tmp/lock';
if (sysopen(FH, $lockfile, O_WRONLY | O_CREAT | O_EXCL)) {
    `your_update_script`;
    close FH;
    unlink $lockfile or die "Can't unlink lockfile $lockfile $!";
    print "Updated";
}
else {
    die "Update already in progress. Aborting!";
}
[download]

cheers

tachyon

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