how to set mount posix=1 option for an existing bind mount?

Cedric Blancher
Fri Aug 11 15:37:29 GMT 2023

On Tue, 8 Aug 2023 at 20:53, Corinna Vinschen <> wrote:
> On Aug  8 16:52, Cedric Blancher via Cygwin wrote:
> > Good afternoon!
> >
> > How do I set mount posix=1 option for an existing bind mount? mount -o
> > remount does not work.
> Did you read
> Mount points created by mount(1) only exist in the current user session,
> and they will disappear with the last process of that user.

Where are the sessions stored? How can I list, create and destroy sessions?

> Our mount(1) doesn't support remount, so you have to unmount and mount
> again.  Again, this only affects the current user session, not other
> users on the system.
> Last but not least, posix=1 is default and is not shown in the output
> of mount(1).  Only posix=0 will be printed.  So this:
>   C:/foo on /home/bar type smbfs (binary,user,bind)
> means the mount point is mounted with posix=1.

But on my Cygwin 4.7 installation C: defaults to posix=1

posix=0 is default for /cygwin/c:
$ mount
C:/cygwin64/bin on /usr/bin type ntfs (binary,auto)
C:/cygwin64/lib on /usr/lib type ntfs (binary,auto)
C:/cygwin64 on / type ntfs (binary,auto)
C: on /cygdrive/c type ntfs (binary,posix=0,user,noumount,auto)

Why? Where do I change the default?

Cedric Blancher <>
Institute Pasteur

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