[系统运维]linux脚本练习

学员命令测试：
1.ifconfig 网卡 可以显示此网卡的信息
? 显示信息中包含此网卡使用的ip地址
? 请用命令过滤此ip并在输出时只显示ip其他信息不显示

[root@westosa mnt]# ifconfig ens3
ens3: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 172.25.254.100  netmask 255.255.255.0  broadcast 172.25.254.255
        inet6 fe80::59cc:1b48:97f1:83c  prefixlen 64  scopeid 0x20<link>
        ether 52:54:00:00:12:12  txqueuelen 1000  (Ethernet)
        RX packets 4259  bytes 8991531 (8.5 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 2530  bytes 372338 (363.6 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

[root@westosa mnt]# ifconfig ens3 | head -n 2 | tail -n 1 | cut -d ' ' -f 10
172.25.254.100

2.找出能登陆系统用户中UID最大的用户，并显示其名称

[root@westosa mnt]# grep bash$ /etc/passwd
root:x:0:0:root:/root:/bin/bash
westos:x:1000:1000:westos:/home/westos:/bin/bash
[root@westosa mnt]# grep bash$ /etc/passwd | sort -t : -k 3 -nr | head -n 1 | cut -d : -f 1
westos

小实验：判断数字范围

[root@westosa mnt]# vim num_check.sh
[root@westosa mnt]# sh num_check.sh 10 
10 is not in 0-9
[root@westosa mnt]# sh num_check.sh 9
9 is in 0-9
[root@westosa mnt]# cat num_check.sh
#!bin/bash
[ "$1" -ge "0" -a "$1" -lt "10" ] && {
	echo $1 is in 0-9
}||{
	echo $1 is not in 0-9
}

学员检测
编写脚本完成以下条件
file_check.sh 在执行时
如果脚本后未指定检测文件报错“未指定检测文件，请指定”
如果脚本后指定文件不存在报错“此文件不存在”
当文件存在时请检测文件类型并显示到输出中

[root@westosa mnt]# vim file_check.sh
//写脚本
[ -z "$1" ] && {
        echo "未指定检测文件，请指定！"
        exit
}

[ -o "$1" ] || {
        echo "此文件不存在"
        exit
}

[ -d "$1" ] && {
        echo "文件类型为目录"
        exit
}

[ -S "$1" ] && {
        echo "文件类型为套接字"
        exit
}

[ -L "$1" ] && {
        echo "文件类型为软链接"
        exit
}

[ -f "$1" ] && {
        echo "文件类型为普通文件"
        exit
}

[ -b "$1" ] && {
        echo "文件类型为块设备"
        exit
}

[ -c "$1" ] && {
        echo "文件类型为字符设备"
        exit
//

练习脚本：
请显示系统中能被su命令切换的用户名称

[root@westosa mnt]# grep -E "bash$|sh$" /etc/passwd | cut -d : -f 1
root

练习及脚本
Apache_port.sh
此脚本接入数字
http的端口就改为此数字
假设selinux为关闭状态
例如：
sh Apache_port.sh
ERROR: Pleaase input port number following script !!

sh Apache_port.sh 8080
apache的端口会被修改为8080

vim Apache_port.sh 
//编写内容
 #!/bin/bash
 setenforce 0 &> /dev/null

 [ -z "$1" ] && {
 echo "Error:Please input port following script !!"
 exit
 }

 rpm -q httpd &> /dev/null || {
 echo "Error:Apache is not installed !!"
 exit
 }
    
 systemctl status httpd | grep "running" &> /dev/null || {
 echo "Error:Apache is not running !!"
 exit
 }
    
 netstat -antlupe | grep -E "$1\>" &> /dev/null && {
  echo "Error:$1 is in used !!"
  exit
  }
  
  sed "/^Listen/cListen $1" -i /etc/httpd/conf/httpd.conf
  systemctl restart httpd

  netstat -antlupe | grep http
//

测试：

[root@localhost mnt]# sh Apache_port.sh 
Error:Please input port following script !!
[root@localhost mnt]# sh Apache_port.sh 8080
tcp6       0      0 :::8080                 :::*                    LISTEN      0          171157     7664/httpd      

课后练习：
统计在系统中能su切换的并且用户加目录不在/home下的用户数量

思路：使用awk命令以：为分隔符截取/etc/passwd文件中第六列不以/home开头的（/需要转译；不能直接写不含有home关键字，存在类似用户家目录为/tmp/home这种情况）、并且以bash或sh结尾的行，对截取结果进行计数，这里我们可以创建用户对脚本进行测试

[root@westoslinux mnt]# vim su.sh
[root@westoslinux mnt]# cat su.sh
awk -F : 'BEGIN{N=0}$6!~/^\/home/&&/bash$|sh$/{N++}END{print N}' /etc/passwd
[root@westoslinux mnt]# useradd -d /tmp/home lee
useradd: cannot set SELinux context for home directory /tmp/home
[root@westoslinux mnt]# sh su.sh
2
[root@westoslinux mnt]# userdel -r lee
userdel: lee mail spool (/var/spool/mail/lee) not found
userdel: lee home directory (/tmp/home) not found
[root@westoslinux mnt]# sh su.sh
1

脚本练习：??
ip_show.sh 网卡?? ?显示当前的IP

vim /mnt/test.sh
//
#!/bin/bash
   [ -z "$1" ] && {
    echo "Error: Please input interface following script !!"
    exit
    }
    
    ifconfig $1 | awk '/\<inet\>/{print $2}'
//
测试：
[root@westoslinux mnt]# sh ip_show.sh ens3
172.25.254.100
[root@westoslinux mnt]# sh ip_show.sh ens10
[root@westoslinux mnt]# sh ip_show.sh westos
westos: error fetching interface information: Device not found

host_messages.sh 显示当前主机的名称，ip登陆当前主机的用户

hostname:?? ?xxxxx
ipaddress:?? ?xxxx.xxxx.xxx.xxx
username:?? ?root

[root@westoslinux mnt]# vim host_messages.sh
[root@westoslinux mnt]# cat host_messages.sh

#!/bin/bash
echo "hostname:               `hostname`"
echo "ipaddress:              `ifconfig ens3|awk '/inet\>/{print $2}'`"
echo "username:             $USER"
[root@westoslinux mnt]# sh host_messages.sh
hostname:               westoslinux.westos.org
ipaddress:              172.25.254.100
username:             root

clear_log.sh?? ?执行次脚本后可以清空日志

[root@westoslinux mnt]# vim clear_log.sh
[root@westoslinux mnt]# sh clear_log.sh
/var/log/messages is cleaned !!
[root@westoslinux mnt]# cat clear_log.sh
#!/bin/bash
[ "$USER" != "root" ] && {
echo "Error: Please run script with root !!"
exit
}

[ ! -e "/var/log/messages" ] && {
echo "Error: not found log file "
exit
}

> /var/log/messages && {
 echo /var/log/messages is cleaned !!
}

# 练习脚本 #
sh create_user.sh
Please input username: westos
westos exist<output>> westos is exist>Please input username:
westos not existplease input password: 无回显密码
此用户会自动建立并且密码为提示后设定的密码
并显示:westos is created
并再次提示Please input username：
当Please input username：exit
此脚本退出

[root@westoslinux ~]# cat create_user.sh
###########################
#Author:            lee
#Version:           1.0
#Create_Time:      2021/08/14
#Mail:             lee@westos.org
#Info:      
#
#
###########################

#!/bin/bash
CREATE()
{
   read -p "Please input username:" NAME
   [ "$NAME" = "exit" ] && {
   exit
   }

   id $NAME &> /dev/null && {
   echo ""
   echo "$NAME is exist"
   echo ""
   CREATE
   }||{
    echo ""
    read -p "Please input password:" -s PASSWD
    useradd $NAME
    echo $PASSWD | passwd --stdin $NAME
    echo ""
    echo "$NAME is created"
    CREATE
    }
}

CREATE

测试：
[root@westoslinux ~]# vim create_user.sh
[root@westoslinux ~]# sh create_user.sh
Please input username:westos

westos is exist

Please input username:lee

Please input password:1Changing password for user lee.
passwd: all authentication tokens updated successfully.

lee is created
Please input username:lee

Please input password:Changing password for user 1lee.
passwd: all authentication tokens updated successfully.

1lee is created
Please input username:exit