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chapter22/function_ping_nodes

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+function ping_nodes
+{
+#######################################################
+#
+# Ping the other systems check
+#
+# This can be disabled if you do not want every node to be pinging all of the
+# other nodes.  It is not necessary for all nodes to ping all other nodes.
+# Although, you do want more than one node doing the pinging just in case
+# the pinging node is down.  To activate pinging the "$PINGNODES" variable
+# must be set to "TRUE".  Any other value will disable pinging from this node.
+#
+
+# set -x  # Uncomment to debug this function
+# set -n # Uncomment to check command syntax without any execution
+
+if [ $PINGNODES = "TRUE" ]
+then
+     echo     # Add a single line to the output
+
+     # Loop through each node in the $PINGLIST
+
+     for HOSTPINGING in $PINGLIST  # Spaces between nodes in the
+                                   # list is assumed
+     do
+          # Inform the user what is going On
+
+          echo "Pinging --> ${HOSTPINGING}...\c"
+
+          # If the pings received back is equal to "0" then you have a
+          # problem.
+
+          # Ping $PING_COUNT times, extract the value for the pings
+          # received back.
+
+          PINGSTAT=$(ping_host $HOSTPINGING | grep transmitted \
+                     | awk '{print $4}')
+
+          # If the value of $PINGSTAT is NULL, then the node is
+          # unknown to this host
+
+          if [[ -z "$PINGSTAT" && "$PINGSTAT" = '' ]]
+          then
+              echo "Unknown host"
+              continue
+          fi
+          if (( $PINGSTAT == 0 ))
+          then    # Let's do it again to make sure it really is reachable
+
+               echo "Unreachable...Trying one more time...\c"
+               sleep $INTERVAL
+               PINGSTAT2=$(ping_host $HOSTPINGING | grep transmitted \
+                         | awk '{print $4}')
+
+               if [ $PINGSTAT2 -eq "0" ]
+               then # It REALLY IS unreachable...Notify!!
+                    echo "Unreachable"
+                    echo "Unable to ping $HOSTPINGING from $THISHOST" \
+                          | tee -a $PING_OUTFILE
+               else
+                    echo "OK"
+               fi
+          else
+               echo "OK"
+          fi
+
+     done
+fi
+}
+