Hi John,
it depend... If you need just access/copy data (saved on datastore) from linux (virtual) machine, the easyest way is enable SSH on ESXi server and use scp from target machine:
scp root@ESXi_IP_address:/vmfs/volumes/storage_name/your_data /path_where_to_copy
If You need to share data, is is possible to mount this data over SCP, but I think, that this is not good idea.
T.