diff --git a/policy.go b/policy.go
index 965ade50..6fff4dfd 100644
--- a/policy.go
+++ b/policy.go
@@ -91,6 +91,17 @@ func (m *syncPolicyManager) ForLevel(level uint32) Policy {
 	return m.PolicyManager.ForLevel(level)
 }
 
+func (m *syncPolicyManager) ForSystem() SystemPolicy {
+	m.RLock()
+	defer m.RUnlock()
+
+	if m.PolicyManager == nil {
+		return SystemPolicy{}
+	}
+
+	return m.PolicyManager.ForSystem()
+}
+
 func (m *syncPolicyManager) Start() error {
 	m.RLock()
 	defer m.RUnlock()
diff --git a/release/install-release.sh b/release/install-release.sh
index 0844369c..094a6e2d 100755
--- a/release/install-release.sh
+++ b/release/install-release.sh
@@ -3,6 +3,11 @@
 # This file is accessible as https://install.direct/go.sh
 # Original source is located at github.com/v2ray/v2ray-core/release/install-release.sh
 
+# If not specify, default meaning of return value:
+# 1: System error
+# 2: Application error
+# 3: Network error
+
 CUR_VER=""
 NEW_VER=""
 ARCH=""
@@ -156,21 +161,24 @@ extract(){
 }
 
 
-# 1: new V2Ray. 0: no
+# 1: new V2Ray. 0: no. 2: not installed. 3: check failed. 4: don't check.
 getVersion(){
     if [[ -n "$VERSION" ]]; then
         NEW_VER="$VERSION"
-        return 1
+        return 4
     else
-        CUR_VER=`/usr/bin/v2ray/v2ray -version 2>/dev/null | head -n 1 | cut -d " " -f2`
+        VER=`/usr/bin/v2ray/v2ray -version 2>/dev/null`
+        RETVAL="$?"
+        CUR_VER=`echo $VER | head -n 1 | cut -d " " -f2`
         TAG_URL="https://api.github.com/repos/v2ray/v2ray-core/releases/latest"
         NEW_VER=`curl ${PROXY} -s ${TAG_URL} --connect-timeout 10| grep 'tag_name' | cut -d\" -f4`
-
         if [[ $? -ne 0 ]] || [[ $NEW_VER == "" ]]; then
             colorEcho ${RED} "Network error! Please check your network or try again."
-            exit
+            return 3
+        elif [[ $RETVAL -ne 0 ]];then
+            return 2
         elif [[ "$NEW_VER" != "$CUR_VER" ]];then
-                return 1
+            return 1
         fi
         return 0
     fi
@@ -186,6 +194,10 @@ stopV2ray(){
     elif [[ -n "${SERVICE_CMD}" ]] || [[ -f "/etc/init.d/v2ray" ]]; then
         ${SERVICE_CMD} v2ray stop
     fi
+    if [[ $? -ne 0 ]]; then
+        colorEcho ${RED} "Failed to shutdown V2Ray service."
+        return 2
+    fi
     return 0
 }
 
@@ -200,19 +212,21 @@ startV2ray(){
     elif [ -n "${SERVICE_CMD}" ] && [ -f "/etc/init.d/v2ray" ]; then
         ${SERVICE_CMD} v2ray start
     fi
+    if [[ $? -ne 0 ]]; then
+        colorEcho ${RED} "Failed to start V2Ray service."
+        return 2
+    fi
     return 0
 }
 
 copyFile() {
     NAME=$1
-    MANDATE=$2
     ERROR=`cp "/tmp/v2ray/v2ray-${NEW_VER}-linux-${VDIS}/${NAME}" "/usr/bin/v2ray/${NAME}" 2>&1`
     if [[ $? -ne 0 ]]; then
         colorEcho ${YELLOW} "${ERROR}"
-        if [ "$MANDATE" = true ]; then
-            exit
-        fi
+        return 2
     fi
+    return 0
 }
 
 makeExecutable() {
@@ -222,30 +236,30 @@ makeExecutable() {
 installV2Ray(){
     # Install V2Ray binary to /usr/bin/v2ray
     mkdir -p /usr/bin/v2ray
-    copyFile v2ray true
+    copyFile v2ray || return $?
     makeExecutable v2ray
-    copyFile v2ctl false
+    copyFile v2ctl
     makeExecutable v2ctl
-    copyFile geoip.dat false
-    copyFile geosite.dat false
+    copyFile geoip.dat
+    copyFile geosite.dat
 
     # Install V2Ray server config to /etc/v2ray
-    mkdir -p /etc/v2ray
     if [[ ! -f "/etc/v2ray/config.json" ]]; then
-      cp "/tmp/v2ray/v2ray-${NEW_VER}-linux-${VDIS}/vpoint_vmess_freedom.json" "/etc/v2ray/config.json"
-      if [[ $? -ne 0 ]]; then
-          colorEcho ${YELLOW} "Create V2Ray configuration file error, pleases create it manually."
-          return 1
-      fi
-      let PORT=$RANDOM+10000
-      UUID=$(cat /proc/sys/kernel/random/uuid)
+        mkdir -p /etc/v2ray
+        cp "/tmp/v2ray/v2ray-${NEW_VER}-linux-${VDIS}/vpoint_vmess_freedom.json" "/etc/v2ray/config.json"
+        if [[ $? -ne 0 ]]; then
+            colorEcho ${YELLOW} "Create V2Ray configuration file error, pleases create it manually."
+            return 1
+        fi
+        let PORT=$RANDOM+10000
+        UUID=$(cat /proc/sys/kernel/random/uuid)
 
-      sed -i "s/10086/${PORT}/g" "/etc/v2ray/config.json"
-      sed -i "s/23ad6b10-8d1a-40f7-8ad0-e3e35cd38297/${UUID}/g" "/etc/v2ray/config.json"
+        sed -i "s/10086/${PORT}/g" "/etc/v2ray/config.json"
+        sed -i "s/23ad6b10-8d1a-40f7-8ad0-e3e35cd38297/${UUID}/g" "/etc/v2ray/config.json"
 
-      colorEcho ${GREEN} "PORT:${PORT}"
-      colorEcho ${GREEN} "UUID:${UUID}"
-      mkdir -p /var/log/v2ray
+        colorEcho ${GREEN} "PORT:${PORT}"
+        colorEcho ${GREEN} "UUID:${UUID}"
+        mkdir -p /var/log/v2ray
     fi
     return 0
 }
@@ -277,7 +291,7 @@ Help(){
     echo "  -h, --help            Show help"
     echo "  -p, --proxy           To download through a proxy server, use -p socks5://127.0.0.1:1080 or -p http://127.0.0.1:3128 etc"
     echo "  -f, --force           Force install"
-    echo "      --version         Install a particular version"
+    echo "      --version         Install a particular version, use --version v3.15"
     echo "  -l, --local           Install from a local file"
     echo "      --remove          Remove installed V2Ray"
     echo "  -c, --check           Check for update"
@@ -335,15 +349,19 @@ remove(){
 }
 
 checkUpdate(){
-        echo "Checking for update."
-        getVersion
-        if [[ $? -eq 1 ]]; then
-            colorEcho ${GREEN} "Found new version ${NEW_VER} for V2Ray."
-            exit 
-        else 
-            colorEcho ${GREEN} "No new version."
-            exit
-        fi
+    echo "Checking for update."
+    VERSION=""
+    getVersion
+    RETVAL="$?"
+    if [[ $RETVAL -eq 1 ]]; then
+        colorEcho ${GREEN} "Found new version ${NEW_VER} for V2Ray.(Current version:$CUR_VER)"
+    elif [[ $RETVAL -eq 0 ]]; then
+        colorEcho ${GREEN} "No new version. Current version is ${NEW_VER}."
+    elif [[ $RETVAL -eq 2 ]]; then
+        colorEcho ${RED} "No V2Ray installed."
+        colorEcho ${GREEN} "The newest version for V2Ray is ${NEW_VER}."
+    fi
+    return 0
 }
 
 main(){
@@ -374,9 +392,14 @@ main(){
         # download via network and extract
         installSoftware "curl" || return $?
         getVersion
-        if [[ $? == 0 ]] && [[ "$FORCE" != "1" ]]; then
+        RETVAL="$?"
+        if [[ $RETVAL == 0 ]] && [[ "$FORCE" != "1" ]]; then
             colorEcho ${GREEN} "Latest version ${NEW_VER} is already installed."
-            exit
+            return
+        elif [[ $RETVAL == 3 ]]; then
+            return 3
+        elif [[ $RETVAL == 1 ]]; then
+            colorEcho ${GREEN} "Found new version ${NEW_VER} for V2Ray.(Current version:$CUR_VER)"
         else
             colorEcho ${BLUE} "Installing V2Ray ${NEW_VER} on ${ARCH}"
             downloadV2Ray || return $?
@@ -388,7 +411,7 @@ main(){
         V2RAY_RUNNING=1
         stopV2ray
     fi
-    installV2Ray
+    installV2Ray || return $?
     installInitScript || return $?
     if [[ ${V2RAY_RUNNING} -eq 1 ]];then
         colorEcho ${BLUE} "Restarting V2Ray service."