SHELL——流程控制条件判断

1、判断当前磁盘剩余空间是否有20G，如果小于20G，则将报警邮件发送给管理员，每天检查一次磁盘剩余空间。

2、判断web服务是否运行

        1）、查看进程的方式判断该程序是否运行

        2）、通过查看端口的方式判断该程序是否运行），如果没有运行，则启动该服务。

3、使用curl命令访问第二题的web服务，看能否正常访问，如果能正常访问，则返回web server is running；如果不能正常访问，返回12状态码。

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1、判断当前磁盘剩余空间是否有20G，如果小于20G，则将报警邮件发送给管理员，每天检查一次磁盘剩余空间。

        1）、服务端和客户端安装mailx和postfix

#服务端
[root@server ~]# yum install postfix -y
[root@server ~]# systemctl enable postfix --now

#客户端
[root@client ~]# yum install sendmail -y

        2）、编写脚本

[root@server ~]# cat mail.sh 
#!/bin/bash
##############################################################
# File Name: zuoye.sh
# Version: V1.0
# Author: xx
# Email: [email protected]
# Organization: http://www.xx.com/xx/
# Created Time : 2023-05-23 19:39:44
# Description:
##############################################################
#1、判断当前磁盘剩余空间是否由20G
free_space1=`df -m | grep -w /boot | tr -s " " " "|cut -d " " -f 4`
free_space2=`df -m | grep -w / | tr -s " " " "|cut -d " " -f 4`
free_sum=$((free_space1+free_space2))
free=$((free_sum/1024))
if [ $free -lt 20 ]
then
  echo 内存空间严重不足！| mail -s "内存报警!" redhat
fi

        3）、运行测试

[root@server ~]# bash mail.sh

[root@server mailx]# systemctl restart postfix.service 
[root@server mailx]# mail redhat
sadsa
EOT
[root@server mailx]# vim /var/spool/mail/redhat

        by server.hostname.com (Postfix) with ESMTPS id 1984E31F5E9C
        for ; Tue, 23 May 2023 19:59:50 +0800 (CST)
Received: (from root@localhost)
        by server.hostname.com (8.16.1/8.16.1/Submit) id 34NBxoEH003618
        for redhat; Tue, 23 May 2023 19:59:50 +0800
From: root 
Message-Id: <[email protected]>
Date: Tue, 23 May 2023 19:59:50 +0800
To: [email protected]
Subject: =?utf-8?B?5YaF5a2Y5oql6K2mIQ==?=
User-Agent: Heirloom mailx 12.5 7/5/10
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 8bit

内存空间严重不足！

       

 

        4）、加入计划任务

[root@server day05]# vim /etc/crontab 

SHELL=/bin/bash
PATH=/sbin:/bin:/usr/sbin:/usr/bin
MAILTO=root

# For details see man 4 crontabs

# Example of job definition:
# .---------------- minute (0 - 59)
# |  .------------- hour (0 - 23)
# |  |  .---------- day of month (1 - 31)
# |  |  |  .------- month (1 - 12) OR jan,feb,mar,apr ...
# |  |  |  |  .---- day of week (0 - 6) (Sunday=0 or 7) OR sun,mon,tue,wed,thu,fri,sat
# |  |  |  |  |
# *  *  *  *  * user-name  command to be executed
0 0 * * * root /root/mail.sh

2、判断web服务是否运行

        1）、查看进程的方式判断该程序是否运行

        2）、通过查看端口的方式判断该程序是否运行），如果没有运行，则启动该服务。

                （1）、下载httpd包

[root@server ~]# yum install httpd -y

               （2）、编写脚本

[root@server ~]# vim httpd.sh

#!/bin/bash
##############################################################
# File Name: httpd.sh
# Version: V1.0
# Author: xx
# Email: [email protected]
# Organization: http://www.xx.com/xx/
# Created Time : 2023-05-21 16:20:15
# Description:
##############################################################
ps_httpd=`ps -ef | grep httpd | grep -v grep | wc -l`
if [[ $ps_httpd > 0 ]];then
  echo "httpd.server is runing"
else
  systemctl start httpd
  systemctl stop firewalld
fi
                                             

         （3）、运行检测

[root@server ~]# bash httpd.sh 
httpd.server is runing

3、使用curl命令访问第二题的web服务，看能否正常访问，如果能正常访问，则返回web server is running；如果不能正常访问，返回12状态码。

        1）、编写脚本

[root@server ~]# vim web.sh

#!/bin/bash
##############################################################
# File Name: web.sh
# Version: V1.0
# Author: xx
# Email: [email protected]
# Organization: http://www.xx.com/xx/
# Created Time : 2023-05-21 16:27:01
# Description:
##############################################################
curl -s 192.168.186.139 > /dev/null
if [[ $? = 0 ]];then
  echo "web server is runing"
else
  exit 12
fi

        2）、运行测试

[root@server ~]# systemctl restart httpd
[root@server ~]# systemctl status httpd
● httpd.service - The Apache HTTP Server
     Loaded: loaded (/usr/lib/systemd/system/httpd.service; disabled; ven>
     Active: active (running) since Sun 2023-05-21 16:31:37 CST; 8s ago
       Docs: man:httpd.service(8)
   Main PID: 5895 (httpd)
     Status: "Started, listening on: port 80"
      Tasks: 213 (limit: 10756)
     Memory: 47.9M
        CPU: 82ms
     CGroup: /system.slice/httpd.service
             ├─5895 /usr/sbin/httpd -DFOREGROUND
             ├─5896 /usr/sbin/httpd -DFOREGROUND
             ├─5897 /usr/sbin/httpd -DFOREGROUND
             ├─5898 /usr/sbin/httpd -DFOREGROUND
             └─5899 /usr/sbin/httpd -DFOREGROUND

5月 21 16:31:35 server.hostname.com systemd[1]: Starting The Apache HTTP >
[root@server ~]# bash web.sh 
web server is runing
[root@server ~]# systemctl stop httpd
[root@server ~]# bash web.sh 
[root@server ~]# echo $?
12
[root@server ~]#