Nagios监控内存状态（check_mem）

    在Nagios监控中，默认是没有check_mem这个插件的，也就是说不能监控内存的使用状态，而swap是可以的。下面贴上check_mem的代码：

#!/bin/bash

# check_mem for Nagios
# http://cto.luxiaok.com
# 2013-03-25

USAGE="`basename $0` [-w|--warning]<percent free:0-99> [-c|--critical]<percent free:0-99>"
THRESHOLD_USAGE="WARNING threshold must be greater than CRITICAL: `basename $0` $*"
critical=""
warning=""
STATE_OK=0
STATE_WARNING=1
STATE_CRITICAL=2
STATE_UNKNOWN=3
# print usage
if [[ $# -lt 4 ]]
then
        echo ""
        echo "Wrong Syntax: `basename $0` $*"
        echo ""
        echo "Usage: $USAGE"
        echo ""
        exit 0
fi
# read input
while [[ $# -gt 0 ]]
  do
        case "$1" in
               -w|--warning)
               shift
               warning=$1
        ;;
               -c|--critical)
               shift
               critical=$1
        ;;
        esac
        shift
  done

# verify input
if [[ $warning -eq $critical || $warning -lt $critical ]]
then
        echo ""
        echo "$THRESHOLD_USAGE"
        echo ""
        echo "Usage: $USAGE"
        echo ""
        exit 0
fi
# Total memory available
total=`free -m | head -2 |tail -1 |gawk '{print $2}'`
# Total memory used
used=`free -m | head -2 |tail -1 |gawk '{print $3}'`
# Calc total minus used
free=`free -m | head -2 |tail -1 |gawk '{print $4+$6+$7}'`
# Free Mem = free + buffers + cached
# Normal values
#echo "$total"MB total
#echo "$used"MB used
#echo "$free"MB free
# make it into % percent free = ((free mem / total mem) * 100)

FREETMP=`expr $free \* 100`
percent=`expr $FREETMP / $total`

if [[ "$percent" -le  $critical ]]
        then
                echo "Critical - $free MB ($percent%) Free Memory"
                exit 2
elif [[ "$percent" -le  $warning ]]
        then
                echo "Warning - $free MB ($percent%) Free Memory"
                exit 1
elif [[ "$percent" -gt  $warning ]]
        then
                echo "OK - $free MB ($percent%) Free Memory"
                exit 0
else
                echo "Unknow Status"
                exit 3
fi

    脚本内容来源于网络，基本是2008年以前的代码，我这里进行了优化和修改。需要注意的是参数-w和-c所匹配的值的十进制的百分数，即0-99，其实到100也没问题。但不要写成了内存的大小，那就悲剧了，不同的Server内存不同，用了多少M或者多少G也不同，所以记住是匹配十进制的百分比。