Date: Fri, 02 Mar 2007 10:02:22 -0600 From: Eric Anderson <anderson@freebsd.org> To: Steven Hartland <killing@multiplay.co.uk> Cc: freebsd-hackers@freebsd.org, Mike Meyer <mwm@mired.org>, freebsd-stable@freebsd.org Subject: Re: Mount on non-empty directories (Was: sysinstall creates corruptfilesystems after repartitioning) Message-ID: <45E84A8E.6040705@freebsd.org> In-Reply-To: <010001c75ce3$6983ded0$b3db87d4@multiplay.co.uk> References: <00cb01c75c5b$4205e390$b3db87d4@multiplay.co.uk><45E82660.4030107@freebsd.org><008101c75cd1$42a4df10$b3db87d4@multiplay.co.uk> <17896.15939.9988.89695@bhuda.mired.org> <010001c75ce3$6983ded0$b3db87d4@multiplay.co.uk>
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On 03/02/07 09:56, Steven Hartland wrote: > Mike Meyer wrote: >> In <008101c75cd1$42a4df10$b3db87d4@multiplay.co.uk>, Steven Hartland >> This is just a special case of mounting on a non-empty directory. It >> should work right. The last mounted file system is the one you get >> (unless you're using a file system that's designed to behave another >> way). If you unmount the directory, the last mounted device is >> unmounted. > > This makes sence but is not what happens hence the confusion. If > the last mounted FS is the one you get that makes sence but in > this case thats not what I observed. Are you sure? In your last email, you described the above interaction exactly (you had an NFS mounted /usr, then you made a new empty /usr, and it mounted it on top, then you couldn't execute things in /usr anymore (vim was your example), then you unmounted the last mounted fs (the empty one), and your vim was accessible again.. ? >> As a general rule, deciding that something is "useless and dangerous" >> and removing it isn't the Unix way of doing things. Just because you >> can't see a use for something doesn't mean that no one else >> will. That's true even if you wrote the code. Someone doing something >> with your program you never thought of is a sign that you developed a >> generally useful tool. As for dangerous, Unix users - especially root, >> and mount is restricted to root by default - are assumed to know what >> they're doing. > > Appreciated but the issue I'm trying to understand is that the result > didn't make any sence i.e. ls returned the files but trying to run > them didnt work. Result my head started to spin a bit :P As mentioned > this seemed to easily resolved by force unmounting the second device > but as has been explained this has a clear use for which I was unaware > but I'd still like to understand by I saw what I did i.e. ls > displayed the files yet running vim didnt. > > I'm going to investigate this more in an effort to determine why I > got these results and report back. Thanks for everyone's feedback > so far most appreciated. Ok, at this point, you need to send df, mount, and your ls output between each step. Eric
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