4.2 Info request: Read-only file systems

[H. Morrow Long [Systems Center]]

In <2483 at nsc.UUCP> chongo writes
> I would like to mount things like /bin, most of /etc, /usr/{bin,lib, ... },
> /dev/{mem,kmem,...}, usw...  on a read-only disc pack.
> 
> What is needed (if it can be done) to be done to unix to allow this?
> 

What you need to do is place the (sub)directory to be read-only in its
own filesystem.  You can then use 'mount /usr/src -r' to mount the
filesystem readonly or change field 3 from ':rw:' to ':ro:' in
/etc/fstab and the 'mount -a' will do it for you.

In the following fstab fragment /usr/src is mounted readonly:

/dev/hp0a:/:rw:1:1
/dev/hp2a:/tmp:rw:0:4
/dev/hp3g:/usr:rw:1:2
/dev/hp0e:/usr/src:ro:1:3

------
>From /etc/rc:

/etc/mount -a							>/dev/console
-------

You can still unmount the filesystem (although you probably wouldn't be
able to umount /bin or /usr/bin if you are in multiuser mode because
they would be in almost continual use) and mount it read-write (the
default) if you need to place a program on it.

-- 

				H. Morrow Long
				ITT-ATC Systems Center,
				1 Research Drive Shelton, CT  06484
				Phone #: (203)-929-7341 x. 634
	
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