下面讲解经典脚本案例，主要是借用其思路。

此种脚本最好用于nagios监控，结合nagios监控脚本比较好。

用法为#./shell/chk_mem.sh -w 数值临界值 -c 数值临界值

给定数值不同，脚本报出信息级别不同，由此判断紧急情况。

#!/bin/bashSTAT_OK=0STAT_WARNING=1STAT_CRITICAL=2STAT_UNKNOWN=3total_mem=`free -m |awk 'NR==2{print $2}'`used_mem=`free -m |awk 'NR==3{print $3}'`free_mem=`free -m |awk 'NR==3{print $4}'`use_per=`echo "scale=2;$used_mem/$total_mem"|bc|sed 's/^.//g'`#free_per=`echo "scale=2;$free_mem/$total_mem"|bc|sed 's/^.//g'`#echo "$use_per"help() { echo "USAGE:`basename $0` [-w] <used percent> [-c] <used percent> [-h]" exit -1}while getopts ":w:c:h" optdo case $opt in w) warning=$OPTARG ;; c) critical=$OPTARG ;; h) help ;; ?) unkown=$OPTARG echo "error,plase check for help,USAGE:./`basename $0` -h" exit $STAT_UNKNOWN ;; esacdoneif [[ $use_per -lt $warning ]]then echo "OK - total:$total_mem MB,used:$used_mem MB,free:$free_mem MB | total_mem=$total_mem used_mem=$used_mem free_mem=$free_mem" exit $STAT_OK elif [[ $use_per -ge $warning ]] && [[ $use_per -lt $critical ]]then echo "WARNING - total:$total_mem MB,used:$used_mem MB,free:$free_mem MB | total_mem=$total_mem used_mem=$used_mem free_mem=$free_mem" exit $STAT_WARNINGelse echo "CRITICAL - total:$total_mem MB,used:$used_mem MB,free:$free_mem MB | total_mem=$total_mem used_mem=$used_mem free_mem=$free_mem" exit $STAT_CRITICAL fifi