diff --git a/update.sh b/update.sh
index 8324779..9acc325 100644
--- a/update.sh
+++ b/update.sh
@@ -15,20 +15,20 @@ fi
 # get OS ditro and version
 OS=$(hostnamectl | awk '/Operating System/ {print $3}')
 VM=$(hostnamectl | awk '/Virtualization/ {print $2}')
-if [ "${OS}" == 'Ubuntu' ]; then
+if [ "${OS}" == "Ubuntu" ]; then
 	OS_VER=$(hostnamectl | awk '/Operating System/ {print $4}')
 else
 	OS_VER=$(hostnamectl | awk '/Operating System/ {print $5}')
 fi
 
-if [ "${VM}" == 'vmware' ]; then
-	VM='true'
+if [ "${VM}" == "vmware" ]; then
+	VM="true"
 else
-	VM='false'
+	VM="false"
 fi
 
 # Debian OS
-if [ ${OS} == 'Debian' ] || [ ${OS} == 'Ubuntu' ]; then
+if [ ${OS} == "Debian" ] || [ ${OS} == "Ubuntu" ]; then
     # upgrade all packages
     apt update; apt upgrade -y
     
@@ -48,8 +48,8 @@ if [ ${OS} == 'Debian' ] || [ ${OS} == 'Ubuntu' ]; then
     apt install -y pbis-open sudo nano htop nload iperf iperf3 unattended-upgrades unzip git nfs-common uptimed net-tools build-essential curl
     
     # install vm tools
-    if [ ${VM} == 'true' ]; then
-    	apt install open-vm-tools
+    if [ "${VM}" == "true" ]; then
+    	apt install -y open-vm-tools
     fi
     
     # remove unneeded packages
@@ -64,7 +64,7 @@ if [ ${OS} == 'Debian' ] || [ ${OS} == 'Ubuntu' ]; then
     update-ca-certificates
 
 # CentOS OS
-elif [ ${OS} == 'CentOS' ]; then
+elif [ "${OS}" == "CentOS" ]; then
     # upgrade all packages
     yum update -y
     
@@ -81,13 +81,13 @@ elif [ ${OS} == 'CentOS' ]; then
     yum autoremove -y
     
     # Centos 7 
-    if [[ ${OS_VER} =~ ^7.* ]]; then
+    if [[ "${OS_VER}" =~ "^7.*" ]]; then
       # install the packages
       yum install -y pbis-open sudo nano htop nload iperf iperf3 bind-utils yum-cron unzip nfs-utils git wget uptimed net-tools make
 
 	  # install vm tools
-      if [ ${VM} == 'true' ]; then
-           yum install open-vm-tools
+      if [ "${VM}" == "true" ]; then
+           yum install -y open-vm-tools
       fi
       
       # modify yum-cron config to auto install security updates and enable/start the service 
@@ -101,15 +101,15 @@ elif [ ${OS} == 'CentOS' ]; then
       systemctl enable uptimed
     fi
     # Centos 7 
-    if [[ ${OS_VER} =~ ^8.* ]]; then
+    if [ "${OS_VER}" =~ "^8.*" ]]; then
    		# install the packages
         # libnsl is needed for pbis and needs to be installed already
         dnf install -y libnsl
       	dnf install -y pbis-open sudo nano htop iperf3 bind-utilsunzip nfs-utils git wget net-tools make
         
         # install vm tools
-        if [ ${VM} == 'true' ]; then
-           dnf install open-vm-tools
+        if [ "${VM}" == "true" ]; then
+           dnf install -y open-vm-tools
         fi
     
         # https://github.com/BeyondTrust/pbis-open/issues/242