Ok ive inherited a number of unix boxes who have drives mounted in different ways. Mostly the nfs filesystems are named in vfstab but some mount points for remote servers are not mentioned in vfs tab and are in fact links to /net/hostname/directory

Does anyone know how this is setup?

Do a man on automount. "man automount"

This is what utilizes the /net mountpoint. The reason they don't show up in the vfstab is that they are not always available to be mounted and your system would hang on boot waiting for these mount points to be visible. Also, they are only available while the are being used. If they are not accessed for a period of time they are unmounted.

Automount allows you to mount these filesystems when they are available and/or needed.

You should have a config file somewhere with "auto" in the name under the /etc directory. On HPUX, it is under /etc/rc.config.d

From the manpage:
automount is a command that installs autofs mount points and
associates an automount map with each mount point. The autofs
filesystem monitors attempts to access directories within it and
notifies the automountd daemon (See automountd(1M)). The daemon uses
the map to locate a filesystem, which it then mounts at the point of
reference within the autofs filesystem. You can assign a map to an
autofs mount using an entry in the /etc/auto_master map or a direct
map.

If the file system is not accessed within an appropriate interval
(five minutes by default), the automountd daemon unmounts the file
system.


Hope this gives you some ideas.

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