jail.8: Add creating a jail from distribution set

PR:			200803
MFC after:		3 days
Reviewed by:		jamie
Differential Revision:	https://reviews.freebsd.org/D53631

usr.sbin/jail/jail.8

@@ -1,3 +1,6 @@
+.\"
+.\" SPDX-License-Identifier: BSD-2-Clause
+.\"
 .\" Copyright (c) 2000, 2003 Robert N. M. Watson
 .\" Copyright (c) 2008-2012 James Gritton
 .\" All rights reserved.
@@ -23,7 +26,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd October 8, 2025
+.Dd November 6, 2025
 .Dt JAIL 8
 .Os
 .Sh NAME
@@ -1120,7 +1123,7 @@ process.
 This manual page documents the configuration steps necessary to support
 either of these steps, although the configuration steps may need to be
 refined based on local requirements.
-.Ss "Setting up a Jail Directory Tree"
+.Ss Setting up a Jail Directory Tree From Source
 To set up a jail directory tree containing an entire
 .Fx
 distribution, the following
@@ -1133,8 +1136,19 @@ mkdir -p $D
 make world DESTDIR=$D
 make distribution DESTDIR=$D
 .Ed
+.Ss Setting up a Jail Directory Tree from Distribution Files
+To set up a jail directory tree containing an entire
+.Fx
+distribution, the following
+.Xr sh 1
+command script can be used:
+.Bd -literal -offset indent
+D=/here/is/the/jail
+mkdir -p $D
+tar -xf /usr/freebsd-dist/base.txz -C $D --unlink
+.Ed
 .Pp
-In many cases this example would put far more in the jail than needed.
+In many cases these examples would put far more in the jail than needed.
 In the other extreme case a jail might contain only one file:
 the executable to be run in the jail.
 .Pp