Add default element selection

This change includes the 'base' element by default and adds a
command line switch to prevent this behaviour. This should reduce
confusion since this element is almost always necessary.

Change-Id: Ib4a2ef53a76b119b764751fa21058f4e2cb37741

bin/disk-image-create

@@ -33,13 +33,14 @@ function show_options () {
     echo "    -x -- turn on tracing"
     echo "    -u -- uncompressed; do not compress the image - larger but faster"
     echo "    -c -- clear environment before starting work"
+    echo "    -n skip the default inclusion of the 'base' element"
     echo "    -p package[,package,package] -- list of packages to install in the image"
     exit 0
 }
 
 INSTALL_PACKAGES=""
 COMPRESS_IMAGE="true"
-TEMP=`getopt -o a:ho:xucp: -n $SCRIPTNAME -- "$@"`
+TEMP=`getopt -o a:ho:xucnp: -n $SCRIPTNAME -- "$@"`
 if [ $? != 0 ] ; then echo "Terminating..." >&2 ; exit 1 ; fi
 
 # Note the quotes around `$TEMP': they are essential!
@@ -53,6 +54,7 @@ while true ; do
         -x) shift; set -x;;
         -u) shift; export COMPRESS_IMAGE="";;
         -c) shift ; export CLEAR_ENV=1;;
+        -n) shift; export SKIP_BASE="1";;
         -p) IFS="," read -a INSTALL_PACKAGES <<< "$2"; export INSTALL_PACKAGES ; shift 2 ;;
         --) shift ; break ;;
         *) echo "Internal error!" ; exit 1 ;;
@@ -67,6 +69,10 @@ fi
 
 for arg do IMAGE_ELEMENT="$IMAGE_ELEMENT $arg" ; done
 
+if [ "$SKIP_BASE" != "1" ]; then
+  IMAGE_ELEMENT="base $IMAGE_ELEMENT"
+fi
+
 source $_LIB/img-defaults
 source $_LIB/common-functions
 source $_LIB/img-functions