--- a/bin/fjail	Thu Aug 15 16:07:53 2019 +0200
+++ b/bin/fjail	Thu Aug 15 17:01:02 2019 +0200
@@ -2,7 +2,7 @@
 # -*- indent-tabs-mode: nil; -*-
 # @(#)$HGid$
 
-set -eu
+set -e
 
 VERSION="@@VERSION@@"
 
@@ -26,6 +26,10 @@
   privs MOUNTPOINT
 
     Adjust some Unix privileges to mounted jail datasets
+
+  populate MOUNTPOINT BASETXZ
+
+    Populate the jail directory in MOUNTPOINT with the base system in BASETXZ
 "
 
 
@@ -117,6 +121,39 @@
 
 
 #
+# "populate" -- populate the datasets with content from a FreeBSD base.txz
+#
+# command_populate mountpoint basetxz
+#
+command_populate() {
+    # MOUNTPOINT -- base.txz
+    local _mp _basetxz
+
+    _mp="$1"
+    _basetxz="$2"
+
+    if [ -z "${_mp}" ]; then
+        echo "ERROR: no mountpoint given" >&2
+        return 2
+    fi
+    if [ -z "${_basetxz}" ]; then
+        echo "ERROR: no base.txz given" >&2
+        return 2
+    fi
+    if [ ! -d "${_mp}" ]; then
+        echo "ERROR: mountpoint \`${_mp}' does not exist" >&2
+        return 1
+    fi
+    if [ ! -r "${_basetxz}" ]; then
+        echo "ERROR: file \`${_basetxz}' is not readable" >&2
+        return 1
+    fi
+
+    tar -C "${_mp}" --exclude=./var/empty -xJp -f "${_basetxz}" || { echo "ERROR: tar encountered errors" >&2; return 1; }
+}
+
+
+#
 # "privs" -- adjust privileges
 #
 # To be used when all ZFS datasets are mounted.
@@ -174,8 +211,11 @@
     privs)
         command_privs "$@"
         ;;
+    populate)
+        command_populate "$@"
+        ;;
     *)
-        echo "ERROR" >&2
+        echo "ERROR: unknown command \`${command}'" >&2
         exit 2
         ;;
 esac