Improve kernel switching methodology

lib/armbian-configng/config.ng.functions.sh

@@ -328,16 +328,14 @@ function switch_kernels() {
 
  # we only allow switching kerneles that are in the test pool
  [[ -z "${KERNEL_TEST_TARGET}" ]] && KERNEL_TEST_TARGET="legacy,current,edge"
- local kernel_test_target="("$(echo $KERNEL_TEST_TARGET | sed "s/,/|/g")")"
- local current_kernel_version=$(dpkg -l | grep '^ii' | grep linux-image | awk '{print $2"="$3}')
-
+ local kernel_test_target=$(for x in ${KERNEL_TEST_TARGET//,/ }; do echo "linux-image-$x-${LINUXFAMILY}"; done;)
+ local installed_kernel_version=$(dpkg -l | grep '^ii' | grep linux-image | awk '{print $2"="$3}')
+ # just in case current is not installed
+ [[ -n ${installed_kernel_version} ]] && local grep_current_kernel=" | grep -v ${installed_kernel_version}"
+ local search_exec="apt-cache show ${kernel_test_target} | grep -E \"Package:|Version:|version:|family\" | grep -v \"Config-Version\" | sed -n -e 's/^.*: //p' | sed 's/\.$//g' | xargs -n3 -d'\n' | sed \"s/ /=/\" $grep_current_kernel"
  IFS=$'\n'
  local LIST=()
- for line in $(
- apt-cache show "linux-image-${kernel_test_target}-${LINUXFAMILY}" | grep -E "Package:|Version:|version:|family" |
- grep -v "Config-Version" | sed -n -e 's/^.*: //p' | sed 's/\.$//g' | xargs -n3 -d'\n' | sed "s/ /=/" |
- grep -v "${current_kernel_version}"
- ); do
+ for line in $(eval ${search_exec}); do
  LIST+=($(echo $line | awk -F ' ' '{print $1 " "}') $(echo $line | awk -F ' ' '{print "v"$2}'))
  done
  unset IFS