safe to use shutdown -h now to bring down system

I'm using the BeagleBoard xM as part of a robotics project and I've
decided to program the user button to safely bring down the system
when pressed. I'm running Ubuntu Maverick from with the
additional packages installed for the xfce desktop. I've written a C++
program that monitors for user button presses from /dev/input/event4,
and then uses an execl() call to issue sudo shutdown -h now command to
bring down the system. I'm wondering, is the best command to use to
safely bring down the system? Also will I need to add any code (I was
thinking some type of signal handler) to other programs I've written
so that they will exit gracefully?


Graham Holland