diff --git a/README.md b/README.md
index 7ed0286..10c3c83 100644
--- a/README.md
+++ b/README.md
@@ -248,6 +248,23 @@ A curated list of awesome Arduino hardwares, libraries and projects
 * [Smart Garden](http://www.instructables.com/id/Smart-Garden-1/?ALLSTEPS) - clone of Erbbie
 * [Temperature controlled craft beer coolbox](http://www.instructables.com/id/temperature-controlled-craft-beer-coolbox/) - a coolbox in which you can control the temperature in three separate compartments 
 
+## usage
+
+```bash
+usage()
+{
+    echo ""
+    echo " usage:"
+    echo ""
+    echo "./update.sh <cmd>"
+    echo "    where <cmd> is one of:"
+    echo "      --install-or-update     (does full installation or update.)"
+    echo "      --remove 		        (removes all installed)"
+    echo ""
+    echo "example:"
+    echo '    $ ./update.sh --install-or-update'
+}
+```
 
 ## Contributing
 * [Contributing](https://github.com/lembed/awesome-arduino/blob/master/CONTRIBUTING.md)
diff --git a/update.sh b/update.sh
new file mode 100644
index 0000000..8a4f61c
--- /dev/null
+++ b/update.sh
@@ -0,0 +1,128 @@
+#!/bin/bash
+
+INFILE='README.md'
+OUTFILE='.tmp'
+
+usage()
+{
+    echo ""
+    echo " usage:"
+    echo ""
+    echo "./update.sh <cmd>"
+    echo "    where <cmd> is one of:"
+    echo "      --install-or-update     (does full installation or update.)"
+    echo "      --remove 		        (removes all installed)"
+    echo ""
+    echo "example:"
+    echo '    $ ./update.sh --install-or-update'
+}
+
+function check
+{
+
+	git --version >/dev/null
+	if [ $? -ne 0 ] 
+	then
+		echo "no git command found ! please download and install"
+		exit
+	fi
+	:
+}
+
+function pure_context
+{
+	# zero list
+	>$2
+
+	for LINE in  $(cat $1)
+	do
+		rs=$(echo $LINE | grep "github" )
+		if [[ "$rs" != "" ]]; then
+			rt=$(echo $LINE | grep "Projects" )
+			if [[ "$rt" !=  "" ]]; then
+				continue
+			fi
+			rl=$(echo $LINE | awk -F '(' '{print $2}' | awk -F ')' '{print $1}' )
+			echo "$rl" >> $OUTFILE
+		fi
+			:
+	done
+}
+
+
+
+function is_git 
+{
+	isg=$(cat $1/.git/config)
+	if [[ "$isg" ==  "" ]]; then
+		return "0"
+	else
+		return "1"
+	fi
+}
+
+
+function do_update
+{	
+
+	for LINE in  $(cat $1)
+	do
+		instant=$(echo $LINE | awk -F '/' '{print $5}' )
+		echo $instant
+		if [[ "$instant" ==  "" ]]; then
+			continue
+			echo "noting"
+		fi
+
+		if [ -d "$instant" ]; then
+			ig=is_git "$instant"
+			if [[ "$ig" ==  "0" ]]; then
+				rm -rf $instant
+				git clone "$LINE" &
+			fi
+			git pull origin master ; echo "$instant"
+		else
+			git clone "$LINE" &
+		fi
+		:
+	done
+}
+
+function do_del
+{	
+
+	for LINE in  $(cat $1)
+	do
+		instant=$(echo $LINE | awk -F '/' '{print $5}' )
+		echo $instant
+		if [[ "$instant" ==  "" ]]; then
+			continue
+		fi
+		echo $instant
+		if [ -d "$instant" ]; then
+			rm -rf $instant	
+		fi
+		:
+	done
+}
+
+
+# main
+check
+
+if [ $# -eq 1 -a "$1" == "--install-or-update" ]; then
+    pure_context $INFILE $OUTFILE
+	do_update $OUTFILE
+	rm -rf $OUTFILE
+    exit
+fi
+
+if [ $# -eq 1 -a "$1" == "--remove" ]; then
+    pure_context $INFILE $OUTFILE
+	do_del $OUTFILE
+	rm -rf $OUTFILE
+    exit
+fi
+
+
+usage
\ No newline at end of file