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Re: New mount option "bind"
On Wed, Aug 11, 2010 at 03:58:38PM +0200, Corinna Vinschen wrote:
>On Aug 11 09:52, Christopher Faylor wrote:
>> On Wed, Aug 11, 2010 at 01:36:59PM +0200, Corinna Vinschen wrote:
>> >Hi guys,
>> >
>> >I added a new mount option "bind" which I took from Linux. It allows to
>> >remount an existing POSIX directory into another POSIX directory. So
>> >the path on the left side of the fstab line can be a POSIX path as well.
>> >At Cygwin startup, when its added to the mount table, it's converted to
>> >a Win32 path using the already existing entries in the mount table to
>> >evaluate the path. So, the path is either relative to a path which
>> >preceeds the "bind" path in /etc/fstab, or it's eventually relative to
>> >the root dir.
>> >
>> >The motivation for this was that this allows to specify mount points
>> >while retaining relocatability of the Cygwin install tree. So, even if
>> >you don't know in which path the Cygwin installation has been installed,
>> >you can do stuff like this now:
>> >
>> > $ cat /etc/fstab
>> > /var /usr/var none bind
>> >
>> > $ mount
>> > C:/cygwin/bin on /usr/bin type ntfs (binary,auto)
>> > C:/cygwin/lib on /usr/lib type ntfs (binary,auto)
>> > C:/cygwin/var on /usr/var type ntfs (binary,bind) <<<<<<<<<<
>> > C:/cygwin on / type ntfs (binary,auto)
>> > C: on /cygdrive/c type ntfs (binary,posix=0,user,noumount,auto)
>> >
>> >I also updated the docs to describe this new option. If you find a
>> >problem with this option, or if the documentation is not good enough,
>> >please feel free to send patches.
>>
>> If the mount for /var changes then is that reflected by /usr/var? I
>> believe that's how it works for linux.
>
>No, that doesn't work in Cygwin. The path is converted to a Win32 path
>as soon as it's read from the fstab file or when you call `mount -o bind ...'
>
>Our mount table does not allow to keep the POSIX->POSIX mapping right
>now, but we could add that at some point. OTOH, I think this scenario
>is really seldom. Usually you have the bind entries in fstab and that
>doesn't change a lot on the fly.
Actually, I don't even know if it works that way in linux but, if it
does, maybe it's worth a note in the documentation.
I'll put it on my todo list to investigate.
cgf