from terminal type mount then hit enter
phila_mac:~ phila$ mount
You will get a result that shows what is mounted where
/dev/disk1s2 on / (hfs, local, journaled)
devfs on /dev (devfs, local, nobrowse)
/dev/disk0s2 on /Volumes/Userdata (hfs, local, journaled)
/dev/disk0s3 on /Volumes/BOOTCAMP (ntfs, local, read-only, noowners)
map -hosts on /net (autofs, nosuid, automounted, nobrowse)
map auto_home on /home (autofs, automounted, nobrowse)
localhost:/wLH33xRMhA0tN_wklHcT5O on /Volumes/MobileBackups (mtmfs, nosuid, read-only, nobrowse)
/dev/disk2s10 on /Volumes/Time Machine (hfs, local, nodev, nosuid, journaled)
/dev/disk2s12 on /Volumes/NP (hfs, local, nodev, nosuid, journaled, noowners)
Then try changing dir to where it's mounted.