显示系统信息

[root@wenzi data]#cat systemInfo.sh 
#/bin/bash
RED="\E[1;31m"
GREEN="\E[1;32m"
END="\E[0m"
echo -e  "$GREEN----------------------Host systeminfo--------------------$END"
echo -e  "HOSTNAME:     $RED`hostname`$END"
echo -e  "IPADDR:       $RED`ifconfig ens160 | grep -Eo '([0-9]{1,3}\.){3}[0-9]{1,3}' | head -n 1`$END"
echo -e  "OSVERSION:    $RED`cat /etc/redhat-release`$END"
echo -e  "KERNEL:       $RED`uname -r`$END"
echo -e  "CPU:         $RED`lscpu | grep 'Model name'| tr -s ' ' | cut -d : -f 2`$END"
echo -e  "MEMORY:       $RED`free -h | grep 'Mem' | tr -s ' ' : | cut -d ':' -f 2`$END"
echo -e  "DISK:         $RED`lsblk | grep '^nv' | tr -s ' ' | cut -d " " -f 4`$END"
echo -e  "$GREEN---------------------------------------------------------$END"

说明：

grep -E 开启拓展正则表达式，-o 仅显示匹配到的数据

([0-9]{1,3}\.){3}[0-9]{1,3}中[0-9]{1,3}表示1到3位数字，{3}表示重复3次，所以整体就是匹配IP地址

tr -s 对指定的字符串去重复

cut 使用对象是一行信息，-d 指定分割字符，-f 依据-d的分割字符将一段信息分为数段，用-f取出第几段

^nv 指以nv开头

批量创建用户并设置随机密码

[root@wenzi data]#cat batchCreateUser.sh 
#!/bin/bash
userNum=$1

for ((i=1;i<=${userNum};i+=1))
do
	useradd wenzi$i
	pwd=`cat /dev/urandom | tr -d -c '[:alnum:]' | head -c 12`
	echo $pwd | passwd --stdin wenzi$i &> /dev/null
	echo wenzi$i:$pwd >> /data/user.log
	echo "wenzi$i is created"
done
[root@wenzi data]#bash batchCreateUser.sh 5
wenzi1 is created
wenzi2 is created
wenzi3 is created
wenzi4 is created
wenzi5 is created
[root@wenzi data]#cat /data/user.log 
wenzi1:aBfx6xKXXWXd
wenzi2:zeiXcSdeECga
wenzi3:XXWhxovUy9o1
wenzi4:mk6wF4gqQxbP
wenzi5:YvcHWo6UYQcP

#删除生成的用户
[root@wenzi data]#for i in {1..5};do userdel -r wenzi$i;done

说明：

/dev/urandom是随机数生成器

[:alnum:] 代表英文大小写字符及数字，即 0-9，A-Z，a-z

tr的-d选项：删除信息中指定内容；-c选项：使用指定字符串的补集替换该字符串；所以tr删除的是非'[:alnum:]'的内容

执行远程主机的脚本

#主机192.168.29.142
[root@wenzi ~]#yum -y install httpd
[root@wenzi ~]#vim /var/www/html/hello.sh
#!/bin/bash
echo "hello world"
[root@wenzi ~]#systemctl start httpd

#主机192.168.29.141
[root@wenzi data]#curl http://192.168.29.142/hello.sh | bash
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    31  100    31    0     0  31000      0 --:--:-- --:--:-- --:--:-- 31000
hello world
[root@wenzi data]#curl -s http://192.168.29.142/hello.sh | bash
hello world

rm命令的安全实现

[root@wenzi data]#vim rm.sh 
#!/bin/bash
warning_color="echo -e \E[1;31m"
end="\E[0m"
dir=/tmp/`date +%F%T`
mkdir $dir
mv $* $dir
${warning_color}Move $* to $dir $end
[root@wenzi data]#chmod 777 /data/rm.sh 
[root@wenzi data]#alias rm='/data/rm.sh'
[root@wenzi data]#touch {1..3}.txt
[root@wenzi data]#ll
total 4
-rw-r--r-- 1 root root   0 Jul 22 10:43 1.txt
-rw-r--r-- 1 root root   0 Jul 22 10:43 2.txt
-rw-r--r-- 1 root root   0 Jul 22 10:43 3.txt
-rw-r--r-- 1 root root 138 Jul 22 10:42 rm.sh
[root@wenzi data]#rm *.txt
Move 1.txt 2.txt 3.txt to /tmp/2023-07-2210:45:20 

说明：

$*：位置变量，代表除了$0（脚本本身名字）以外，所有的参数，如上即 “opt1 opt2 opt3 opt4“，每个变量之间用空格分割，共用一个双引号

检查软件包是否安装

[root@wenzi wenzi]# cat test.sh
#!/bin/bash
pkg=$1
rpm -q $1 > /dev/null
if [ $? -eq 0  ];then
        echo "$1 is already installed."
else
        echo "$1 is not installed!"
fi


[root@wenzi wenzi]# ./test.sh httpd
httpd is already installed.
[root@wenzi wenzi]# ./test.sh nginx
nginx is not installed!

检查服务状态

[root@wenzi wenzi]# cat test.sh
#!/bin/bash
if pgrep $1 > /dev/null;then
        echo "$1 is running"
else
        echo "$1 is not running"
fi

[root@wenzi wenzi]# ./test.sh httpd
httpd is running
[root@wenzi wenzi]# ./test.sh nginx
nginx is not running