--- a/thermostat-ng.sh	Tue Aug 08 12:25:15 2017 +0200
+++ b/thermostat-ng.sh	Wed Aug 09 14:25:37 2017 +0200
@@ -3,12 +3,17 @@
 # Runs Thermostat.next() all-in-one locally
 #
 # Examples:
-# 
-# Don't build agent/gateway from source, just run it:
-#  $ BUILD=false ./thermostat-ng
+#
+# Build everything and run thermostat:
+#  $ ./thermostat-ng -a     OR
+#  $ ./thermostat-ng -b all
 #
-# Build agent/gateway from source and run it:
-#  $ ./thermostat-ng
+# Build only agent and run thermostat:
+#  $ ./thermostat-ng -b agent
+#
+# Run thermostat without any build:
+#  $ ./thermostat-ng -b none OR
+#  $ ./thermostat-ng -s
 #
 #set -xv
 #set -e
@@ -73,7 +78,7 @@
 
 # Start/Stop mongodb
 mongodb() {
-  local action="$1"  
+  local action="$1"
   case $action in
     start)
       ;& # fall-through
@@ -123,7 +128,7 @@
 
 # Start/stop web-gateway
 web_gateway() {
-  local action="$1"  
+  local action="$1"
   case $action in
     start)
       start_web_gateway
@@ -141,7 +146,7 @@
   local fail_msg="Failed to start agent"
   config_agent
   echo "Starting agent ..."
-  $AGENT_ROOT/distribution/target/image/bin/thermostat -J-Dthermostat.agent.verbose=true -Tbg "$AGENT_PID_FILE" > "$AGENT_LOG_FILE" 2>&1 
+  $AGENT_ROOT/distribution/target/image/bin/thermostat -J-Dthermostat.agent.verbose=true -Tbg "$AGENT_PID_FILE" > "$AGENT_LOG_FILE" 2>&1
   check_success_msg $? $fail_msg
   wait_for_ready "Agent started" "$AGENT_LOG_FILE"
   check_success_msg $? $fail_msg
@@ -156,7 +161,7 @@
 
 # Start/stop agent
 agent() {
-  local action="$1"  
+  local action="$1"
   case $action in
     start)
       start_agent
@@ -181,7 +186,7 @@
       error=$?
     popd
     check_success_msg $error "Failed to build $component"
-  else 
+  else
     echo "Build of $dir is skipped."
   fi
 }
@@ -215,7 +220,7 @@
     cp $AGENT_ROOT/distribution/target/image/etc/examples/ssl.properties.example $AGENT_ROOT/distribution/target/image/etc/ssl.properties
   else
    sed sX\\\\X/Xg $AGENT_ROOT/distribution/target/image/etc/examples/ssl.properties.example >$AGENT_ROOT/distribution/target/image/etc/ssl.properties
-  fi 
+  fi
 }
 
 
@@ -291,16 +296,139 @@
 
 mkdir -p "$LOG_DIR" "$PID_DIR"
 
+PARTIAL_BUILD=false
+WEB_GATEWAY=true
+WEB_CLIENT=true
+AGENT=true
+
+HELP_STRING="\nUSAGE: $0 [BUILD_OPTION]
+    -a
+        Build everything. No values are bound to this flag.
+    -b [module_names...]|all|none
+        Specify which modules should be built. In case the -b flag has more than one value, it should be specified as the last flag.
+        It is possible to specify more than one value via repetition of this flag, e.g. $0 -b agent -b web-client
+    -s
+        Skip build of all components and directly start Thermostat. No values are bound to this flag.\n\n"
+
+print_help() {
+  printf "$HELP_STRING"
+}
+
+mark_everything_to_be_built() {
+  WEB_GATEWAY=true
+  WEB_CLIENT=true
+  AGENT=true
+}
+
+mark_nothing_to_be_built() {
+  WEB_GATEWAY=false
+  WEB_CLIENT=false
+  AGENT=false
+}
+
+# Check whether the component passed as the first argument of this function exists.
+# "all" is also acceptable as a parameter, which results in the same behaviour as if all components were specified.
+# Component name can also end with a forward slash (UNIX autocompletion support).
+resolve_component_name() {
+  local component_name
+  component_name=$1
+  case "${component_name}" in
+    web-gateway|web-gateway/)
+      WEB_GATEWAY=true
+      ;;
+    web-client|web-client/)
+      WEB_CLIENT=true
+      ;;
+    agent|agent/)
+      AGENT=true
+      ;;
+    none)
+      mark_nothing_to_be_built
+      ;;
+    all)
+      mark_everything_to_be_built
+      ;;
+    *)
+      echo "Component '${component_name}' does not exist."
+      print_help
+      exit 1
+  esac
+}
+
+build_all_requested_components() {
+  if [ "$WEB_GATEWAY" = "true" ]; then
+    build_web_gateway
+  fi
+  if [ "$WEB_CLIENT" = "true" ]; then
+    build_web_client; copy_web_client_to_web_gateway
+  fi
+  if [ "$AGENT" = "true" ]; then
+    build_agent
+  fi
+}
+
+check_for_remaining_components() {
+  # Iterate through remaining arguments and consider them as component names
+  local remaining_args_count remaining_args
+  remaining_args_count=$1
+  remaining_args=$2
+  if [ "$PARTIAL_BUILD" = "true" ]; then
+    for comp in ${remaining_args}; do
+      resolve_component_name $comp
+    done
+  elif [ "$remaining_args_count" -ne "0" ]; then
+    print_help
+    exit 1
+  fi
+}
+
+parse_args() {
+  local OPTIND
+  OPTIND=1
+  while getopts ":b:as" opt ; do
+    case "${opt}" in
+      a)
+        mark_everything_to_be_built
+        break
+        ;;
+      b)
+        if [ "$PARTIAL_BUILD" = "false" ]; then
+          # First occurence of -b flag, first assume no components are going to be built
+          # (by default, all components are going to be built if no flags are specified)
+          # and then resolve component names with $PARTIAL_BUILD=true afterwards.
+          mark_nothing_to_be_built
+          PARTIAL_BUILD=true
+        fi
+        resolve_component_name $OPTARG
+        ;;
+      s)
+        mark_nothing_to_be_built
+        break
+        ;;
+      :)
+        printf "\nOption '$OPTARG' requires parameters."
+        print_help
+        exit 1
+        ;;
+      *)
+        printf "Unexpected option '$OPTARG'"
+        print_help
+        exit 1
+        ;;
+    esac
+  done
+  shift $((OPTIND-1))
+  #OPTIND is local
+  check_for_remaining_components $# $@
+}
+
+parse_args "$@"
+
 # Be sure source tree looks OK.
 check_sources_sane
 
-# Build the agent and web-gateway
-build_agent
-build_web_gateway
-# Build the web client and copy the built distribution image into
-# web-gateway's web-client folder for static serving of the web client.
-build_web_client
-copy_web_client_to_web_gateway
+# Build all components that were requested in command line arguments.
+build_all_requested_components
 
 trap stop_all INT