SCCS-vsn: sbin/mount_union/mount_union.8 8.4
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-.\" @(#)mount_union.8 8.3 (Berkeley) %G%
+.\" @(#)mount_union.8 8.4 (Berkeley) %G%
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.Dd
.Dt MOUNT_UNION 8
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.Dd
.Dt MOUNT_UNION 8
.Nm mount_union
is setuid root and can be used by any user.
To enforce filesystem security, the user must be superuser or else
.Nm mount_union
is setuid root and can be used by any user.
To enforce filesystem security, the user must be superuser or else
-have write permission on the mounted on directory.
+have write permission on the mounted-on directory.
-Filenames are looked up firstly in the upper layer and then in the
+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
lower layer.
If a directory is found in the lower layer, and there is no entry
in the upper layer, then a
The union operation applies recursively down the directory tree
now rooted at
.Ar uniondir .
The union operation applies recursively down the directory tree
now rooted at
.Ar uniondir .
+Thus any filesystems which are mounted under
+.Ar uniondir
+will take part in the union operation.
This differs from the
.Em union
option to
.Xr mount 8
which only applies the union operation to the mount point itself,
and then only for lookups.
This differs from the
.Em union
option to
.Xr mount 8
which only applies the union operation to the mount point itself,
and then only for lookups.
-This also means that any filesystems which are mounted under
-.Ar uniondir
-will take part in the union operation.
.Sh OPTIONS
The options are:
.Bl -tag -width indent
.Sh OPTIONS
The options are:
.Bl -tag -width indent
accessible via
.Pa /sys .
.Sh SEE ALSO
accessible via
.Pa /sys .
.Sh SEE ALSO
.Xr mount 2 ,
.Xr unmount 2 ,
.Xr fstab 5 ,
.Xr mount 2 ,
.Xr unmount 2 ,
.Xr fstab 5 ,