run script on shutdown

Question

I have the following script, how do I run it on shutdown in debian linux? (don't want to use GUI)

#!/bin/bash
vms=$(vmrun list | grep '/');
for vm in ${vms}
do
        echo 'suspending ' $vm
        vmrun suspend $vm soft
done

I tried adding it to /usr/local/bin with chmod +x permissions. Then I created symbolic links to rc0.d (shutdown) and rc6.d (reboot).

I then did update-rc.d shutdown_vms 0 6 .

When I do shutdown -r now, it switches to console mode to restart....at that point I can see a error message stating shutdown_vms has failed.

I this the proper way to install the shutdown script and why is it failing (where do I look in the logs?)