linux服务器内存、负载过高自动重启apache脚本

由于好玩吧的centos服务器用的是阿里云的服务器，内存只有1G，最近升级了2G，感觉还是操作起来还是很卡，wordpress又巨吃内存。无奈为了避免内存溢出服务器挂掉，采取shell脚本来执行

代码如下：

#mkdir -p /data/software/restart_apache/

#vi /data/software/restart_apache/loadavg_restart_apache.sh

以下内容：

#!/bin/sh
# crontab: */3 * * * * /data/software/restart_apache/loadavg_restart_apache.sh >> /data/software/restart_apache/restart_apache.log
#TOP_SYS_LOAD_NUM表示到达这个负载的时候，就会停止apache。然后过段时间负载降下来后，再尝试启动apache（单核建议1，双核2）
TOP_SYS_LOAD_NUM=1
SYS_LOAD_NUM=`uptime | awk '{print $(NF-2)}' | sed 's/,//'`
#MIN_RAM表示系统可用内存如果小于此设置的时候（单位MB），就会停止apache。然后过段时间负载降下来后，再尝试启动apache
MIN_RAM=100
FREE_RAM=`free -m| grep Mem|awk '{print $4}'`
echo $(date +"%y-%m-%d") `uptime`
if [ `echo "$TOP_SYS_LOAD_NUM < $SYS_LOAD_NUM"|bc` -eq 1 ] ||  [ `echo "$FREE_RAM < $MIN_RAM"|bc` -eq 1 ]
then
    echo "#0#" $(date +"%y-%m-%d %H:%M:%S") "pkill httpd" `ps -ef | grep httpd | wc -l`
    #/usr/sbin/apachectl stop
	/etc/init.d/httpd stop
    sleep 8		#休眠8秒之后
    pkill httpd
    sleep 8
    for i in 1 2 3
    do
        if [ `pgrep httpd | wc -l` -le 0 ]
        then
            #/usr/sbin/apachectl start
			/etc/init.d/httpd start
            sleep 30
            echo "#1#" $(date +"%y-%m-%d %H:%M:%S") "start httpd" `ps -ef | grep httpd | wc -l`
        fi
    done
else
    if [ `pgrep httpd | wc -l` -le 0 ]
    then
        #/usr/sbin/apachectl start
		/etc/init.d/httpd start
        sleep 30
        echo "#2#" $(date +"%y-%m-%d %H:%M:%S") "start httpd" `ps -ef | grep httpd | wc -l`
    fi
fi 

chmod +x /data/software/restart_apache/loadavg_restart_apache.sh

echo
‘*/3 * * * * /data/software/restart_apache/loadavg_restart_apache.sh
>> /data/software/restart_apache/restart_apache.log’ >>
/etc/crontab

监控日志文件：

tail -f /data/software/restart_apache/restart_apache.log

如果脚本执行如果报错

/backup/www.cthome.com/loadavg_restart_apache.sh: line 6: bc: command not found
/backup/www.cthome.com/loadavg_restart_apache.sh: line 6: [: -eq: unary operator expected

表示没有bc命令，centos可以用 yum -y install bc 安装它

参考：http://www.ctohome.com/FuWuQi/e0/404.html