Programatically detect when decryption is done?

Hi all

I am trying to decrypt PDP 10.x encrypted drive on an XP machine as a art of an OS deployment with SCCM 2012 (non bootable media process). I can start the process by running the

PGPwde.exe --decrypt --passphrase ""passphrase"" --disk 0 --dedicated-mode"

works fine. what I cannot find is a way to detect when the process is done, so i can reboot. The PGPwde.exe process runs only until the actual decryption starts. is there any hidden command line to run the reboot pst decryption? Any other suggestions how to effeciently do this?

Thank you.