add version checker for shiny server

shiny_version_check.sh

+#!/bin/bash
+# check for new shiny version and download it if necessary
+
+#set -x
+#trap read debug
+
+rawstring=$(curl -s https://rstudio.com/products/shiny/download-server/ubuntu/ |grep "wget.*amd64.deb")
+prefix="<code>$ "
+suffix="</code><br />"
+noprefix=${rawstring#$prefix}
+nosuffix=${noprefix%$suffix}
+dlcommand="$nosuffix -q -P /home/monitoring/"
+cur_version=$(shiny-server --version | head -n1 | cut -d "v" -f 3)
+avail_version=$(cut -d "-" -f 4 <<< "$dlcommand")
+
+if [ "$avail_version" != "$cur_version" ]
+  then
+    if [ ! -e /home/monitoring/shiny-server-"${avail_version}"-amd64.deb ]
+      then
+        eval "$dlcommand"
+    fi
+    echo "Shiny version $avail_version available (in use $cur_version)"
+fi
+