diff --git a/update.sh b/update.sh
index 8a4f61c..e74e50d 100644
--- a/update.sh
+++ b/update.sh
@@ -1,22 +1,48 @@
 #!/bin/bash
 
+# the script get the master brach of the github repo, clone it to local with git
+# or delete the repo directly.
+# 
+# for get pure url, first get the url list and print to tmp file, and will be delete
+# at the end.
+# 
+# require : the script need to run in git bash
+# 			or system with git installed
+# 			
+# the script use awk, grep, cat to do work
+# 
+# usage : sh update.sh
+# 
 INFILE='README.md'
 OUTFILE='.tmp'
 
-usage()
+DEBUG=''
+
+# print usage
+function usage
 {
     echo ""
     echo " usage:"
     echo ""
-    echo "./update.sh <cmd>"
+    echo "sh 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'
+    echo '    $ sh update.sh --install-or-update'
 }
 
+# for debug
+function printvar
+{
+	if [[ "$DEBUG" != "" ]]; then
+		echo $1
+	fi
+	:
+}
+
+# find the git is installed
 function check
 {
 
@@ -29,29 +55,33 @@ function check
 	:
 }
 
-function pure_context
+# find and write the list to file
+function pure_list
 {
-	# zero list
+	# clean list
 	>$2
 
+	# loop the line of the readme
 	for LINE in  $(cat $1)
 	do
 		rs=$(echo $LINE | grep "github" )
 		if [[ "$rs" != "" ]]; then
+			# the projects list can not be installed
 			rt=$(echo $LINE | grep "Projects" )
 			if [[ "$rt" !=  "" ]]; then
 				continue
 			fi
 			rl=$(echo $LINE | awk -F '(' '{print $2}' | awk -F ')' '{print $1}' )
-			echo "$rl" >> $OUTFILE
+			# write list
+			echo "$rl" >> $2
 		fi
 			:
 	done
 }
 
 
-
-function is_git 
+# find the git dir
+function is_git
 {
 	isg=$(cat $1/.git/config)
 	if [[ "$isg" ==  "" ]]; then
@@ -61,26 +91,27 @@ function is_git
 	fi
 }
 
-
+# git clone the repo , update if it is exist
 function do_update
 {	
-
+	# loop the line of the readme
 	for LINE in  $(cat $1)
 	do
 		instant=$(echo $LINE | awk -F '/' '{print $5}' )
-		echo $instant
+		printvar $instant
 		if [[ "$instant" ==  "" ]]; then
 			continue
-			echo "noting"
+			printvar "noting"
 		fi
 
 		if [ -d "$instant" ]; then
+			# find the dir is git dir or not
 			ig=is_git "$instant"
 			if [[ "$ig" ==  "0" ]]; then
 				rm -rf $instant
 				git clone "$LINE" &
 			fi
-			git pull origin master ; echo "$instant"
+			git pull origin master ; printvar "$instant"
 		else
 			git clone "$LINE" &
 		fi
@@ -88,17 +119,19 @@ function do_update
 	done
 }
 
+# delete the repo, through the list in the list file, so it need to get 
+# the list first
 function do_del
 {	
 
 	for LINE in  $(cat $1)
 	do
 		instant=$(echo $LINE | awk -F '/' '{print $5}' )
-		echo $instant
+		printvar $instant
 		if [[ "$instant" ==  "" ]]; then
 			continue
 		fi
-		echo $instant
+		printvar $instant
 		if [ -d "$instant" ]; then
 			rm -rf $instant	
 		fi
@@ -111,14 +144,20 @@ function do_del
 check
 
 if [ $# -eq 1 -a "$1" == "--install-or-update" ]; then
-    pure_context $INFILE $OUTFILE
+	if [ ! -f "$OUTFILE" ]; then
+    pure_list $INFILE $OUTFILE
+	fi
 	do_update $OUTFILE
 	rm -rf $OUTFILE
     exit
 fi
 
 if [ $# -eq 1 -a "$1" == "--remove" ]; then
-    pure_context $INFILE $OUTFILE
+
+	if [ ! -f "$OUTFILE" ]; then
+    pure_list $INFILE $OUTFILE
+	fi
+
 	do_del $OUTFILE
 	rm -rf $OUTFILE
     exit