--- a/docs/man/man8/ftjail-freebsd-update.rst	Fri Dec 02 21:29:26 2022 +0100
+++ b/docs/man/man8/ftjail-freebsd-update.rst	Fri Dec 02 22:01:43 2022 +0100
@@ -20,6 +20,12 @@
 
 .. program:: ftjail freebsd-update
 
+.. option:: -k
+
+   Keep all temporary files.
+
+   .. note:: On unexpected errors temp files are automatically kept.
+
 
 Environment
 -----------

--- a/sbin/ftjail	Fri Dec 02 21:29:26 2022 +0100
+++ b/sbin/ftjail	Fri Dec 02 22:01:43 2022 +0100
@@ -44,7 +44,7 @@
 
   build-etcupdate-current-tmpl DIRECTORY TARBALL
 
-  freebsd-update DIRECTORY
+  freebsd-update -[-k] DIRECTORY
 
 ENVIRONMENT:
 
@@ -878,12 +878,27 @@
 #:
 command_freebsd_update() {
     local _directory
+    local _opt_keep
 
     local _res _jailname _dir_mounts _dir_fn_fstab _dir_basename
     local _root_dataset _root_mountpoint _root_type _root_options
-    local _dummy
+    local _dummy _opt
     local _root_readonly
 
+    _opt_keep="no"
+    while getopts "k" _opt ; do
+        case ${_opt} in
+            k)
+                _opt_keep="yes"
+                ;;
+            \?|:)
+                return 2;
+                ;;
+        esac
+    done
+    shift $((OPTIND-1))
+    OPTIND=1
+
     _directory="${1-}"
 
     [ -z "${_directory}" ] && { echo "ERROR: no directory given" 1>&2; return 2; }
@@ -936,7 +951,11 @@
     #          al.)  if needed: clone RW, mount, make the dirs,
     #          umount, make the clone RO and continue "normally" by
     #          completely mounting the stored fstab.
-    # 
+    #
+
+    if [ "${_opt_keep}" != "yes" ]; then
+        [ -n "${_dir_fn_fstab}" ] && [ -f "${_dir_fn_fstab}" ] && rm -f "${_dir_fn_fstab}"
+    fi
 }