add version checker for rstudio server

rstudio_version_check.sh

+#!/bin/bash
+# check for new rstudio and download it if necessary
+
+set -e
+
+rawstring=$(curl -s https://www.rstudio.com/products/rstudio/download-server/ |grep -o "wget.*amd64.deb")
+prefix="$"
+suffix="<br />"
+noprefix=${rawstring#$prefix}
+nosuffix=${noprefix%$suffix}
+dlcommand="$(echo $nosuffix -q -P /home/monitoring/)"
+cur_version=$(rstudio-server version)
+avail_version="$(echo $dlcommand | cut -d "-" -f 3)"
+if [ "$avail_version" == "$cur_version" ]
+  then
+    echo "RStudio up to date."
+  else
+    if [ ! -e /home/monitoring/rstudio-server-${avail_version}-amd64.deb ]
+      then
+        eval $dlcommand
+    fi
+    echo "RStudio version $avail_version available (in use $cur_version)"
+fi
+