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.Dd March 15, 2022
.Dt NULLFS 5
.Os
.Sh NAME
.Nm nullfs
.Nd "null file system"
.Sh SYNOPSIS
To enable support for this driver,
place the following line in the kernel configuration file:
.Bd -ragged -offset indent
.Cd "options NULLFS"
.Ed
.Pp
Alternatively, to load the driver as a
module at boot time, place the following line in
.Xr loader.conf 5 :
.Bd -literal -offset indent
nullfs_load="YES"
.Ed
.Sh DESCRIPTION
The
.Nm
driver will permit the
.Fx
kernel to mount a loopback file system sub-tree.
.Sh EXAMPLES
To mount a
.Nm
file system:
.Pp
.Dl "mount_nullfs /usr/ports /home/devel/ports"
.Pp
It is also possible to define an entry in
.Xr fstab 5
that looks similar to:
.Pp
.Bd -literal
/usr/ports	/home/devel/ports	nullfs		rw	0	0
.Ed
.Sh SEE ALSO
.Xr fstab 5 ,
.Xr mount_nullfs 8
.Sh HISTORY
The
.Nm
layer first appeared in
.Bx 4.4 .
.Sh AUTHORS
.An -nosplit
The
.Nm
kernel implementation was written by
.An John Heideman .
.Pp
This manual page was written by
.An Daniel Gerzo Aq Mt danger@FreeBSD.org .