该脚本用于监控VPS服务器负载，Web程序内存及CPU使用。当服务器系统负载或内存使用达到预设值，则重启该程序，或者某个php-cgi进程占用CPU过大，则直接kill掉该进程。目的在于缓解服务器资源耗尽导致意外宕机等情况。
shell脚本内容：
#! /bin/bash
#====================================================================
# sys-mon.sh
#
# Copyright (c) 2011, WangYan <webmaster@wangyan.org>
# All rights reserved.
# Distributed under the GNU General Public License, version 3.0.
#
# Monitor system mem and load, if too high, restart some service.
#
# See: https://wangyan.org/blog/sys-mon-shell-script.html
#
# V 0.5, Date: 2011-12-08
#====================================================================
# Need to monitor the service name
# Must be in /etc/init.d folder exists
NAME_LIST="httpd nginx mysql"
# Single process to allow the maximum CPU (%)
PID_CPU_MAX="25"
# The maximum allowed memory (%)
PID_MEM_SUM_MAX="95"
# The maximum allowed system load
SYS_LOAD_MAX="6"
# Log path settings
LOG_PATH="/var/log/sys-mon.log"
# Date time format setting
DATA_TIME=$(date +"%y-%m-%d %H:%M:%S")
# Your email address
EMAIL="g@ruher.info"
# Your website url
MY_URL="http://www.ruher.info/p.php"
#====================================================================
for NAME in $NAME_LIST
do
PID_CPU_SUM="0";PID_MEM_SUM="0"
PID_LIST=`ps aux | grep $NAME | grep -v root`
IFS_TMP="$IFS";IFS=$'\n'
for PID in $PID_LIST
do
PID_NUM=`echo $PID | awk '{print $2}'`
PID_CPU=`echo $PID | awk '{print $3}'`
PID_MEM=`echo $PID | awk '{print $4}'`
# echo "$NAME: PID_NUM($PID_NUM) PID_CPU($PID_CPU) PID_MEM($PID_MEM)"
PID_CPU_SUM=`echo "$PID_CPU_SUM + $PID_CPU" | bc`
PID_MEM_SUM=`echo "$PID_MEM_SUM + $PID_MEM" | bc`
if [ `echo "$PID_CPU >= $PID_CPU_MAX" | bc` -eq 1 ];then
if [[ "$NAME" = "php-fpm" || "$NAME" = "httpd" ]];then
sleep 5
if [ `echo "$PID_CPU >= $PID_CPU_MAX" | bc` -eq 1 ];then
echo "${DATA_TIME}: kill ${NAME}($PID_NUM) successful (CPU:$PID_CPU)" | tee -a $LOG_PATH
kill $PID_NUM
fi
else
echo "${DATA_TIME}: [WARNING!] ${NAME}($PID_NUM) cpu usage is too high! (CPU:$PID_CPU)" | tee -a $LOG_PATH
fi
fi
done
IFS="$IFS_TMP"
SYS_LOAD=`uptime | awk '{print $(NF-2)}' | sed 's/,//'`
SYS_MON="CPU:$PID_CPU_SUM MEM:$PID_MEM_SUM LOAD:$SYS_LOAD"
# echo -e "$NAME: $SYS_MON\n"
SYS_LOAD_TOO_HIGH=`awk 'BEGIN{print('$SYS_LOAD'>'$SYS_LOAD_MAX')}'`
PID_MEM_SUM_TOO_HIGH=`awk 'BEGIN{print('$PID_MEM_SUM'>'$PID_MEM_SUM_MAX')}'`
if [[ "$SYS_LOAD_TOO_HIGH" = "1" || "$PID_MEM_SUM_TOO_HIGH" = "1" ]];then
/etc/init.d/$NAME stop
sleep 5
for ((i=1;i<4;i++))
do
if [ `pgrep $NAME | wc -l` = "0" ];then
echo "$DATA_TIME: Stop $NAME successful! ($SYS_MON)" | tee -a $LOG_PATH
break
else
echo "${DATA_TIME}: [WARNING!] Stop $NAME failed[$i]! ($SYS_MON)" | tee -a $LOG_PATH
pkill $NAME && killall $NAME
fi
done
/etc/init.d/$NAME start
sleep 5
for ((ii=1;ii<4;ii++))
do
if [ `pgrep $NAME | wc -l` != "0" ];then
echo "$DATA_TIME: Start $NAME successful!" | tee -a $LOG_PATH
break
else
echo "${DATA_TIME}: [WARNING!] Start $NAME failed[$ii]! ($SYS_MON)" | tee -a $LOG_PATH
/etc/init.d/$NAME start
sleep 5
fi
done
if [ `pgrep $NAME | wc -l` != "0" ];then
echo "${DATA_TIME}: [ERROR!] Start $NAME failed! ($SYS_MON)" | mail -s "Start $NAME failed" $EMAIL
fi
fi
done
STATUS_CODE=`curl -o /dev/null -s -w %{http_code} $MY_URL`
#echo -e "STATUS CODE: $STATUS_CODE\n"
if [ "$STATUS_CODE" != "200" ];then
sleep 3
STATUS_CODE=`curl -o /dev/null -s -w %{http_code} $MY_URL`
if [ "$STATUS_CODE" != "200" ];then
echo "${DATA_TIME}: [WARNING!] Website Downtime! ($SYS_MON)" | tee -a $LOG_PATH
echo "${DATA_TIME}: [WARNING!] Website Downtime! ($SYS_MON)" | mail -s "Start $NAME failed" $EMAIL
fi
fi
以上代码保存为一个文件，例如：auto_reboot.sh
添加计划任务，设置每分钟检查一次
crontab -e
* * * * * /bin/bash/root/auto_reboot.sh
注意文件的位置要搞正确。
请确保您的linux系统中已经安装了bc，否则会出现错误。查看是否安装了bc可以使用命令：
bc -v
如果没有安装，centos可以用 yum -y install bc 安装它
可以使用命令
sh /bin/bash/root/auto_reboot.sh
