1-22-shell脚本基本应用-实验手册

脚本应用思路

1. 确定命令操作（设计并执行任务）

2. 编写Shell脚本（组织任务过程）

3. 设置计划任务（控制时间，调用任务脚本）

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实战-1、实现管理员在登录系统时显示如下信息

1)当前运行的进程数量

2)当前系统的登录用户的数量

3)当前使用的磁盘根分区的使用情况

操作过程如下图：

注意：也可修改/etc/profile配置文件，实现开机运行

脚本源码如下：

#!/bin/bash
# welcome information for login
#
# Print below information:
# 1. The total number of processes.
# 2. The totla number of users who logged in.
# 3. The used status of disk.

echo "##########     Welcome!     ##########"
# 1. The total number of processes.
echo "The total number of processes is $(ps -aux | wc -l)."

# 2. The totla number of users who logged in.
echo "The totla number of users who logged in is $(who | wc -l)."

# 3. The used status of disk.
echo "The used status of disk is $(df -hT | grep root | awk '{print $6}')."

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实战-2、编写脚本实现系统服务启动 停止 当前状态的脚本

#!/bin/bash
#service manager script
# status start stop restart

if [ $1 = 'start' ] #start server of $2
    then systemctl start $2 2>>server.logs
elif [ $1 = 'stop' ]  #stop server of $2
    then systemctl stop $2 2>>server.logs
elif [ $1 = 'status' ]  #status server of $2
    then systemctl status $2 2>>server.logs
elif [ $1 = 'restart' ]  #restart server of $2
    then systemctl restart $2 2>>server.logs
fi

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实战-3、写运行状况监控脚本

/sh/monitor.sh，用于记录CPU负载、内存和交换空间、磁盘空间、最近的用户登录情况等信息，以及当时的时间信息。

#!/bin/bash
#back monitor CPU Mem Swap Disk LastLogin information to file

# set recored Dir
Dir=/var/log/runrec/

# prepare the environment
mkdir -p $Dir

# get current time
RecTime=$(date +"%Y-%m-%d %H:%M")

# set record filename
RecFile=$Dir$RecTime.log

# get CPU
RecLoad=$(uptime)

# get Mem and Swap
RecMem=$(free -m)

# get Disk
RecDisk=$(df -hT)

# get Last
RecLastLogin=$(last -n 20)

# echo information and saved to RecFile
echo "######################################
Cpu Load information:$RecLoad
Memory information:$RecMem
Disk Usage information:$RecDisk
Last Login 20 users record:$RecLastLogin" >> $RecFile

设置定时备份：

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实战-4、过滤出本机echo网卡的MAC地址，并赋值给hwaddr

[root@xiaogan121 sh]# ifconfig | grep ether | awk '{ print $2 }'
00:0c:29:af:03:b2
00:0c:29:af:03:bc
52:54:00:83:20:8c
[root@xiaogan121 sh]# ip=$(ifconfig | grep ether | awk '{ print $2 }')
[root@xiaogan121 sh]# echo $ip
00:0c:29:af:03:b2 00:0c:29:af:03:bc 52:54:00:83:20:8c
[root@xiaogan121 sh]#

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实战-5、编写脚本计算当前的内存使用百分比

MemTotal=$(free -m | grep Mem | awk '{ print $2 }')

MemUse=$(free -m | grep Mem | awk '{ print $3 }')

usage=$( expr $( expr  $MemUse * 100 ) / $MemTotal  )

[root@xiaogan121 sh]# usage=$( expr $( expr $(free -m | grep Mem | awk '{ print $3 }') * 100 ) / $(free -m | grep Mem | awk '{ print $2 }') )
[root@xiaogan121 sh]# echo $usage
31
[root@xiaogan121 sh]# free -m | grep Mem | awk '{ print $3 }'
311
[root@xiaogan121 sh]# free -m | grep Mem | awk '{ print $2 }'
977
[root@xiaogan121 sh]# free -m
              total        used        free      shared  buff/cache   available
Mem:            977         312         292           7         373         474
Swap:          2047           0        2047
[root@xiaogan121 sh]#

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实战-6、计算3 4 的平方和