Multiple instances of the same mount point in fstab not possible? (want to layer multiple filesystems into one namespace via union mount option)

[Matthias Petermann <mp%petermann-it.de@localhost>]

Hello all,

I have a possibly somewhat strange question. In addition to the root 
file system, I have three other FFS file systems here. I want to layer 
them on top of each other using the union mount option on one and the 
same mount point.

This works without any problems on the command line. However, I cannot 
find a way to automate this via fstab:


```
NAME=data1             /export   ffs     rw,log,union          0 0
NAME=data2             /export   ffs     rw,log,union          0 0
NAME=data3             /export   ffs     rw,log,union          0 0
```

Here, only the first file system is mounted, the other two are ignored. 
I suspect that multiple occurrences of the same mount point are not 
supported in fstab.

Is my understanding of this correct, and is there perhaps a halfway 
elegant way to implement this?

Kind regards
Matthias