[root@devel3 root]# cat test.pl
#!/usr/bin/perl
my $dat = '/tmp/dat';
my $dir = '/root/';
if ( -e $dat ) {
    `ls -al $dir > $dat.current`;
    if ( `cat $dat` eq `cat $dat.current` ) {
        print "Dir $dir probably unchanged!\n";
    }
    else {
        print "Dir $dir has changed\n", `diff -b $dat $dat.current`;
        `cat $dat.current > $dat`;
    }
}
else {
    `ls -al $dir > $dat`; # first pass init
}
[root@devel3 root]# ./test.pl   # init stage
[root@devel3 root]# ./test.pl
Dir /root/ probably unchanged!
[root@devel3 root]# touch foo
[root@devel3 root]# ./test.pl
Dir /root/ has changed
22a22
> -rw-r--r--    1 root     root            0 Feb 17 20:57 foo
[root@devel3 root]# touch test.pl
[root@devel3 root]# ./test.pl
Dir /root/ has changed
56c56
< -rwxr-xr-x    1 root     root          385 Feb 17 20:57 test.pl
---
> -rwxr-xr-x    1 root     root          385 Feb 17 20:58 test.pl
[root@devel3 root]#