Re: [Off-topic] Plusieurs partitions sur le meme point de montage.

[Stephane Bortzmeyer <bortzmeyer@pasteur.fr>]

On Wednesday 19 January 2000, at 10 h 23, the keyboard of Olivier Rossel 
<o-rossel@ti.com> wrote:

> Est-il vrai que les *BSD ont un systeme de fichier qui permet de monter
> plusieurs devices sur le meme point de montage?

FreeBSD a ça en tout cas. Très pratique pour les CD-ROMs. Cela s'appelle une union:

MOUNT_UNION(8)          FreeBSD System Manager's Manual         MOUNT_UNION(8)

NAME
     mount_union - mount union filesystems

SYNOPSIS
     mount_union [-br] [-o options] directory uniondir

DESCRIPTION
     The mount_union command attaches directory above uniondir in such a way
     that the contents of both directory trees remain visible.  By default,
     directory becomes the upper layer and uniondir becomes the lower layer.

     The options are as follows:

     -b      Invert the default position, so that directory becomes the lower
             layer and uniondir becomes the upper layer.  However, uniondir
             remains the mount point.

     -o      Options are specified with a -o flag followed by a comma separat-
             ed string of options.  See the mount(8) man page for possible op-
             tions and their meanings.

     -r      Hide the lower layer completely in the same way as mounting with
             mount_null(8).

     To enforce filesystem security, the user mounting the filesystem must be
     superuser or else have write permission on the mounted-on directory.

     Filenames are looked up in the upper layer and then in the lower layer.
     If a directory is found in the lower layer, and there is no entry in the
     upper layer, then a shadow directory will be created in the upper layer.
     It will be owned by the user who originally did the union mount, with
     mode ``rwxrwxrwx'' (0777) modified by the umask in effect at that time.