Original Question:
When I issue the mount command without any options I get an overview
over the mounted dilesystems and their mountpoint. Everything I can
see there is clear, except this line:
file-on-file mount on /usr/opt/svr4/etc/saf/_cmdpipe type ffm (rw,
nogrpid)
Can somebody please tell me what file-tofile mount means and where
this line is originating from. I didn't find anything about that in
the archives. Version of OS is 4.0F.
Answers:
Nikola Milutinovic
> I think it has to do something with STREAMS module. Anyway, you can't mount it
> manually.
> Well, I've never seen it on any of my machines. Since it cannot be unmounted,
> it
> really indicates some internal operation. Try looking into that machine,
> especially network. Maybe it is nothing, but then we would all be seeing it a
> lot, wouldn't we?
Lars Bro
> When you use STREAMS, you can "tie a descriptor into the file system"
> which means that, for instance standard-input is suddenly a file.
>
> It is done like this:
>
> $ cat main.c
> #include <stropts.h>
>
> main()
> {
> char ch;
> if (fattach(0,"mystdin")<0)
> perror("fattach");
>
> while(read(0,ch,1)==1)
> write(1,ch,1);
>
> }
>
> $ mkdir mystdin
> $ cc main.c
> $ ./a.out
>
> And then from another terminal
> $ echo xxxxx >> mystdin
>
> The funny thing is that in order to install a whole new set of operations
> into one specific path name, that path name needs to be a mount point. And
> therefore a mount point is created.
>
> Try the above, it is fun. And it can of course be used for several purposes,
> for example
> this saf thing. (In sysV, pipes are STREAMS).
>
> [what cannot be done with sockets is connecting to another process and then
> link this
> connection down into the file system]
Received on Fri Mar 03 2000 - 13:24:56 NZDT