Re: mount_union info (was mount_overlay info)

[Jukka Salmi <j+nbsd%2008.salmi.ch@localhost>]

David Dudley --> current-users (2008-11-12 14:03:45 -0600):
> Yes, looking through general info, I found that command.
> 
> Can mount_union mount a directory above a device?  I mean mount a
> read-write mount point above a read-only CD?

Yes:

$ mount /mnt/cdrom
$ mount
[...]
/dev/cd0a on /mnt/cdrom type cd9660 (read-only, local)
$ echo test >/mnt/cdrom/file
ksh: cannot create /mnt/cdrom/file: Read-only file system
$ mkdir /var/tmp/test
$ mount_union /var/tmp/test /mnt/cdrom
$ mount
[...]
/dev/cd0a on /mnt/cdrom type cd9660 (read-only, local)
<above>:/var/tmp/test on /mnt/cdrom type union (local)
$ cat /mnt/cdrom/test
cat: /mnt/cdrom/test: No such file or directory
$ echo test >/mnt/cdrom/file
$ cat /mnt/cdrom/file
test


Regards, Jukka

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