check_mem.sh

#!/bin/bash
#TH v0.2 30/08/2013
#Quick and Dirty Memory SNMP Poller

if [ $# -le 3 ] && [ $# -gt 5 ]; then
 echo "Usage: $0 <hostname> <SNMP-comunity> <warning> <critical> <optional - Port>"
 echo "Warning and Critical must be in percent"
 echo "e.g 10.10.10.1 public 80 90"
 exit 127
fi

HOST=$1
COMUNITY=$2
WARN=$3
CRITICAL=$4

if [ -z $5 ]; then
 PORT=161
 else
  PORT=$5
fi

#make sure warning is less than critical
if [ "$WARN" -ge "$CRITICAL" ]; then
  echo "WArning must be less than critical"
  exit 127
fi

DiskUse() {
snmpdf -r 3 -t 1 -v 2c -c "$COMUNITY" "$HOST":$PORT 2> /dev/null |head -6|tail -5|awk '{print $3" "$4" "$5'}
}
DISKUSE=(`DiskUse`)

#check at this point that the probe worked and quit if it failed
#this is kinda crap, but the alterntive is not using bash
if [ "${#DISKUSE[@]}" -ne 15 ]; then
 echo "SNMP problem. No data received from host."
 exit 3
fi

TOTAL=${DISKUSE[0]}
USED=${DISKUSE[1]}
BUFFERS=${DISKUSE[7]}
CACHE=${DISKUSE[10]}
REALUSED=$(($USED - $CACHE - $BUFFERS))
#bash does not like floating point numbers
printf -v PERCENTF "%.0f" `echo "scale=50; 100/$TOTAL*$REALUSED"|bc`

if [ "$PERCENTF" -ge "$WARN" ] && [ "$PERCENTF" -le "$CRITICAL" ]; then
 echo "MEMORY WARNING - ${PERCENTF}% Used|Total ${TOTAL}KB, Buffers ${BUFFERS}KB, Cached ${CACHE}KB, Used ${REALUSED}KB"
 exit 1
elif [ "$PERCENTF" -ge "$CRITICAL" ]; then
 echo "MEMORY CRITICAL - ${PERCENTF}% Used|Total ${TOTAL}KB, Buffers ${BUFFERS}KB, Cached ${CACHE}KB, Used ${REALUSED}KB"
 exit 2
else
 echo "MEMORY OK - ${PERCENTF}% Used|Total ${TOTAL}KB, Buffers ${BUFFERS}KB, Cached ${CACHE}KB, Used ${REALUSED}KB"
 exit 0
fi