mount -u effects

Polytropon freebsd at
Tue Dec 11 07:43:54 UTC 2012

On Tue, 11 Dec 2012 10:55:10 +0330, takCoder wrote:
> via googling, i found out that i can use "mount -u" on the mentioned
> device, and then after doing whatsoever needed, when i restart my server
> the ro permission will be back via applying old fstab..

You could have found it out by refering to "man mount". :-)

> but i have no idea what kind of effects it may have on my server.. i
> couldn't find anything but suggestions about not to use this so often.. and
> i really need to know why?? cause my bsd server is not allowed to be missed
> almost at all..
> i think that because this -u option is just increasing my permissions in
> this case, there won't be a danger for my server. is that true?!

There are _few_ side effects that _may_ apply when using the -u
option. From the manual:

The -u flag indicates that the status of an already mounted file
system should be changed.  Any of the options discussed above
(the -o option) may be changed; also a file system can be changed
from read-only to read-write or vice versa.  An attempt to change
from read-write to read-only will fail if any files on the file
system are currently open for writing unless the -f flag is also
specified.  The set of options is determined by applying the
options specified in the argument to -o and finally applying the
-r or -w option.

So I'd say you should always take care that write operations
are finished properly (and so brought to an end).

Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...

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