diff options
Diffstat (limited to 'sbin/mount_null/mount_null.8')
-rw-r--r-- | sbin/mount_null/mount_null.8 | 30 |
1 files changed, 21 insertions, 9 deletions
diff --git a/sbin/mount_null/mount_null.8 b/sbin/mount_null/mount_null.8 index 1a47b27..38473fa 100644 --- a/sbin/mount_null/mount_null.8 +++ b/sbin/mount_null/mount_null.8 @@ -34,15 +34,16 @@ .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" -.\" @(#)mount_null.8 8.4 (Berkeley) 4/19/94 -.\" $Id$ +.\" @(#)mount_null.8 8.6 (Berkeley) 5/1/95 +.\" $Id: mount_null.8,v 1.7 1997/02/22 14:32:50 peter Exp $ .\" -.Dd April 19, 1994 +.Dd May 1, 1995 .Dt MOUNT_NULL 8 .Os BSD 4.4 .Sh NAME .Nm mount_null -.Nd demonstrate the use of a null file system layer +.Nd mount a loopback filesystem sub-tree; +demonstrate the use of a null file system layer .Sh SYNOPSIS .Nm mount_null .Op Fl o Ar options @@ -54,11 +55,22 @@ The command creates a null layer, duplicating a sub-tree of the file system name space under another part of the global file system namespace. -In this respect, it is -similar to the loopback file system (see -.Xr mount_lofs 8 ) . -It differs from -the loopback file system in two respects: it is implemented using +This allows existing files and directories to be accessed +using a different pathname. +.Pp +The primary differences between a virtual copy of the filesystem +and a symbolic link are that +.Xr getcwd 3 +functions correctly in the virtual copy, and that other filesystems +may be mounted on the virtual copy without affecting the original. +A different device number for the virtual copy is returned by +.Xr stat 2 , +but in other respects it is indistinguishable from the original. +.Pp +The +.Nm mount_null +filesystem differs from a traditional +loopback file system in two respects: it is implemented using a stackable layers techniques, and it's .Do null-node |