Eject an external drive after backup

[shoopdawoop]

Not an issue really, but a question: I am using Counterpart to backup to an external drive and I would like to eject the drive after the backup is finished.

I put my eject command in a seperate script and it is working fine:

wait 60 /usr/sbin/diskutil list | grep MyBackupVolume | cut -c 69-75 | (while read i; do /usr/sbin/diskutil unmountDisk $i; done)

So I run my eject.sh script right before counterpart exits, but that never works; possibly because counterpart is still running at that point?

So.. how is this done properly?