Or more concisely, without needing to enable any hidden menus:
for i in /Volumes/*; do
bless --info "$i"
done | sed -ne 's/.*blessed folder is //p'
gets a list of blessed folders on currently mounted volumes. (It's the presence of a blessed folder that makes the volume bootable.)
Note that MacOS 9 blessed folders, if any, will be included in the list. If you need to distinguish them in the output:
for i in /Volumes/*; do
bless --info "$i"
done | sed -ne 's/.*\(OS .\) blessed folder is /\1: /p'
(Code tested under Tiger and Lion.)
To get
just the list of mount points of OS-X bootable volumes:
for i in /Volumes/*; do
bless --info "$i"
done | sed -ne 's/.*OS X blessed folder is \(.*\)System\/Library\/CoreServices$/\1/p'
