test for syntax errors

.githooks/post-checkout

@@ -30,7 +30,7 @@ if [ -f $CHECKOUT_HISTORY_FILE ]; then
             readarray opkg_commands < <(cat $OPKG_COMMANDS_FILE)
             for opkg_c in "${opkg_commands[@]}"; do
                 # check for empty lines
-                if [[ -n $opkg_c ]]; then
+                if [ "$opkg_c" ]; then
                     echo "CC=$opkg_c"
                     # check if line is not starting with '#'
                     if ! grep -qE "^\s*[#]+.*$" <<< "$opkg_c"; then