add script to be used by zabbix agent to parse output file

readOutput.sh

@@ -0,0 +1,81 @@
+#!/bin/bash
+
+#
+# Copyright (c) 2018 leopold@shdx.org
+# Author: Der_Leopold
+#
+# This script simply parses the text file created by readSensor.sh and
+# prints the requested value. It is supposed to be called by the Zabbix
+# agent.
+# To prevent processing of stale data, it compares the timestamp from
+# the file to the current one and returns an error if the difference is
+# too big.
+#
+
+# Maximum data age in seconds. If the data is older, print an error and exit.
+MAXAGE=300
+
+# File to read the sensor data from
+DATAFILE=/opt/Zabbix-DHT/output
+
+function print_usage () {
+    echo ""
+    echo "Usage:"
+    echo ""
+    echo "  readOutput.sh <temperature|humidity>"
+    echo ""
+}
+
+function parse_datafile () {
+#    REGEX="^(\w+)=(\d+\.*\d*)$"  # should work but does not?
+    REGEX="^(\w+)=(.*)$"
+    while read -r LINE; do
+        if [[ $LINE =~ $REGEX ]]; then
+	    KEY=${BASH_REMATCH[1]}
+	    VALUE=${BASH_REMATCH[2]}
+            case $KEY in
+                "Timestamp")
+		    THRESHOLD=$(( $VALUE + $MAXAGE ))
+		    TS=$(date +"%s")
+		    if (( $TS <= $THRESHOLD )); then
+		        TSVALID=1
+		    fi
+                    ;;
+                "Temperature")
+                    if [ $PARAM == "temperature" ]; then
+		        RESULT=$VALUE
+		    fi
+		    ;;
+                "Humidity")
+		    if [ $PARAM == "humidity" ]; then
+                        RESULT=$VALUE
+                    fi
+		    ;;
+            esac
+        fi
+    done < "$DATAFILE"
+}
+
+PARAM="$1"
+
+if [[ ( ! $# -eq 1 ) || ( $PARAM != "temperature" && $PARAM != "humidity" ) ]]; then
+    print_usage
+    exit 1
+fi
+
+if [ ! -r $DATAFILE ]; then
+    echo "Error: cannot read data file"
+    exit 1
+else
+    TSVALID=0
+    parse_datafile
+fi
+
+if [ $TSVALID -eq 0 ]; then
+    echo "Error: Data file contains old or invalid data"
+    exit 1
+else
+    echo "$RESULT"
+    exit 0
+fi
+