case 模式匹配
一、case语法结构
case 变量名 in 模式1) 命令序列1 ;; 模式2) 命令序列2 ;; 模式3) 命令序列3 ;; *） 无匹配后命令序列 esac
在某种意义上，case语句是if语句的简洁版，case语句适合做字符串模式匹配，如果不同的字符值对应不同的功能则用case语句实现，case无法做比较以及测试命令，最后一个模式可以省略;;
command -v 命令用来测试是否是一个命令看$?返回值即可
1.1根据系统版本匹配yum源文件
#!/bin/bash yum_server=192.168.81.250 os_version=$(cat /etc/redhat-release |awk '{print $(NF-1)}'| awk -F '.' '{print $1"."$2}') [ -d /etc/yum.repos.d/bak ] || mkdir -p /etc/yum.repos.d/bak mv /etc/yum.repos.d/* /etc/yum.repos.d/bak &>/dev/null case "$os_version" in "7.6") cat > /etc/yum.repos.d/centos7u6.repo <<-EOF [centos7u6] name=centos7u6 baseurl=file:///media enabled=1 gpgcheck=0 EOF echo "$os_version yum config finish...." ;; "6.5") wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-6.repo echo "$os_version yum config finish...." ;; "5.4") wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-5.repo echo "$os_version yum config finish...." ;; *) echo "error os_version" esac echo "finish.."
1.2删除用户，根据输入的字符确认是否删除
#!/bin/bash -------------------if实现----------------- read -p "please input a delete username: " user id $user &>/dev/null if [ $? -ne 0 ];then echo "no such user: $user" exit 1 //设置退出状态码 fi read -p "are you sure delete: $user [y/n]" action if [ "$action" = y -o "$action" = "yes" -o "$action" = "Y" -o "$action" = "YES" ];then userdel -r $user &>/dev/null echo "$uer is del..." else echo "you is quit" fi -------------------------case实现----------------- read -p "please input a delete username: " user id $user &>/dev/null if [ $? -ne 0 ];then echo "no such user: $user" exit 1 fi read -p "are you sure delete: $user [y/n]" action case $action in y|Y|yes|YES) userdel -r $user &>/dev/null echo "$user is del..." ;; *) echo "you is quit" esac
1.3测试某个文件是否是一个命令
#!/bin/bash command1=/bin/date if command -v $command1 &>/dev/null;then : else echo " $command is not keywords" fi
1.4利用case+if实现批量创建用户
#!/bin/bash read -p "please input prefix: " prefix if [ -z $prefix ];then echo "error prefix" exit 1 fi read -p "please input create num: " num if [[ ! $num =~ ^[0-9]+$ ]];then echo "error num" exit 2 fi read -p "are you sure create {prefix+num} user[y/n]: " action case $action in y|Y|yes|YES) echo "begin create....." for i in `seq $num` do user=$prefix$i useradd $user &>/dev/null if [ $? -eq 0 ];then echo "123" | passwd --stdin $user &>/dev/null fi echo "$user is add....." done ;; n|N|no|NO) echo "scripts is quit...." esac
1.4利用case+if实现批量删除用户
#!/bin/bash read -p "please input prefix: " prefix if [ -z $prefix ];then echo "error prefix" exit 1 fi read -p "please input delete num: " num if [[ ! $num =~ ^[0-9]+$ ]];then echo "error num" exit 2 fi read -p "are you sure delete {prefix+num} user[y/n]: " action case $action in y|Y|yes|YES) echo "begin delete....." for i in `seq $num` do user=$prefix$i userdel -r $user &>/dev/null echo "$user is del....." done ;; n|N|no|NO) echo "scripts is quit...." esac
1.5case实现编译安装软件
#!/bin/bash ############################################################################################### # # # case编译安装工具箱 jxl--20200225 # # # ############################################################################################### tools_dir=/software apache_tools_dir=/software/httpd-2.2.17.tar.gz mysql_tools_dir=/software/mysql-5.5.22.tar.gz cmake_tools_dir=/software/cmake-2.8.6.tar.gz nginx_tools_dir=/software/nginx-1.6.0.tar.gz echo -e "\033[33m begin checking software...\033[0m" yum list installed | grep 'gcc-c++' &>/dev/null if [ $? -ne 0 ];then read -p "system not gcc,do you install gcc-c++? [y|n]: " action case $action in y|Y) yum -y install gcc-c++ if [ $? -eq 0 ];then echo -e "\033[32m gcc-c++ is installed... \033[0m" fi ;; n|N) echo -e "\033[31m no gcc-c++ not install tools... \033[0m" echo -e "\033[31m scripts is quit... \033[0m" exit 1 ;; esac fi echo -e "\033[31m Can install the tool:[httpd|mysql|nginx] \033[0m" read -p "please input install tool: " tool case $tool in httpd) read -p "are you sure install apache_httpd [y|n]: " action_httpd if [ "$action_httpd" = "y" -o "$action_httpd" = "yes" ];then yum -y remove httpd tar xvf $apache_tools_dir -C $tools_dir cd $tools_dir/httpd-2.2.17 ./configure --prefix=/usr/local/httpd --enable-so --enable-rewrite --enable-charset-lite --enable-cgi && make && make install ln -s /usr/local/httpd/bin* /usr/local/bin &>/dev/null cp /usr/local/httpd/bin/apachectl /etc/init.d/httpd sed -i -e '1a # chkconfig:35 85 21' /etc/init.d/httpd sed -i -e '2a # description:Startup script for the Apache HTTP Server' /etc/init.d/httpd systemctl start httpd systemctl enable httpd netstat -lnpt | grep httpd if [ $? -eq 0 ];then echo -e "\033[32m httpd installed....\033[0m" fi elif [ "$action_httpd" = "n" -o "$action_httpd" = "no" ];then echo -e "\033[31m scripts is quit... \033[0m" exit 1 else echo -e "\033[31m error action \033[0m" exit 2 fi curl -I 127.0.0.1 &>/dev/null if [ $? -eq 0 ];then echo -e "\033[32m web page is ok...\033[0m" fi ;; mysql) read -p "are you sure install mysql [y|n]: " action_mysql if [ "$action_mysql" = "y" -o "$action_mysql" = "yes" ];then yum -y remove mariadb yum -y install ncurses-devel tar xvf $cmake_tools_dir -C $tools_dir cd $tools_dir/cmake-2.8.6 ./configure && make && make install tar -xvf $mysql_tools_dir -C $tools_dir cd $tools_dir/mysql-5.5.22 cmake -DCMAKE_INSTALL_PREFIX=/usr/local/mysql -DDEFAULT_CHARSET=utf8 -DDEFAULT_COLLATION=utf8_general_ci -DWICH_EXTRA_CHARSETS=all -DSYSCONFDIR=/etc && make &&make install \cp -rf support-files/my-medium.cnf /etc/my.cnf \cp -rf support-files/mysql.server /etc/init.d/mysqld chmod +x /etc/init.d/mysqld ln -s /usr/local/mysql/bin/* /usr/local/bin &>/dev/null groupadd mysql &>/dev/null useradd -M -s /sbin/nologin -g mysql mysql &>/dev/null chown -R mysql:mysql /usr/local/mysql /usr/local/mysql/scripts/mysql_install_db --basedir=/usr/local/mysql/ --datadir=/usr/local/mysql/data/ --user=mysql /etc/init.d/mysqld start netstat -lnpt | grep mysql if [ $? -eq 0 ];then echo -e "\033[32m mysqld installed...\033[0m" fi elif [ "$action_mysql" = "n" -o "$action_mysql" = "no" ];then echo -e "\033[31m scripts is quit... \033[0m" exit 1 else echo -e "\033[31m error action... \033[0m" exit 2 fi ;; nginx) read -p "are you sure install mysql [y|n]: " action_nginx if [ "$action_nginx" = "y" -o "$action_nginx" = "yes" ];then yum -y install openssl-devel zlib-devel pcre-devel tar -xvf $nginx_tools_dir -C $tools_dir cd $tools_dir/nginx-1.6.0 ./configure --prefix=/usr/local/nginx --with-http_ssl_module && make && make install netstat -lnpt | grep 80 if [ $? -eq 0 ];then echo -e "\033[32m port 80 is used...\033[0m" echo -e "\033[33m begin update port is 8888!\033[0m" sed -i 's/80;/8888;/' /usr/local/nginx/conf/nginx.conf if [ $? -eq 0 ];then echo -e "\033[33m port is 8888...\033[0m" fi fi ln -s /usr/local/nginx/sbin/* /usr/local/sbin &>/dev/null nginx netstat -lnpt | grep nginx if [ $? -eq 0 ];then echo -e "\033[32m nginx installed...\033[0m" fi elif [ "$action_nginx" = "n" -o "$action_nginx" = "no" ];then echo -e "\033[31m scripts is quit... \033[0m" exit 1 else echo -e "\033[31m error action... \033[0m" exit 2 fi ;; *) echo -e "\033[31m The tool is still in development...\033[0m" esac
1.6case实现简单的跳板机
跳板机适用场景：
1.业务服务器不允许直接连接，通过跳板机进行连接
2.业务服务器不允许root用户登录
跳板机原理
由客户端登录到跳板机服务器，跳板机服务器根据用户输入的ip远程连接对应的应用服务器，客户端不能直接与应用服务器直连，所有主机准备远程连接时使用的账号密码，并设置为密码验证或者密钥验证
此案例需求：
1.做出一个服务器列表
2.根据用户的输入判断去连接哪一台服务器
3.用户连到跳板机服务器就已经将脚本运行好
4.连接进去后不允许退出
#!/bin/bash clear trap "" INT HUP OUIT TSTP while : do cat <<-EOF +---------------------------------------------------------+ | jumpserver | | 1.192.168.81.210 | | 2.192.168.81.211 | | 3.192.168.81.212 | | 4.192.168.81.213 | +---------------------------------------------------------+ EOF echo -en "\e[33m please input connection host: \e[0m" read host case $host in 1) ssh jxl@192.168.81.210 ;; 2) ssh jxl@192.168.81.211 ;; 3) ssh jxl@192.168.81.212 ;; 4) ssh jxl@192.168.81.213 ;; "") ;; *) echo "The host does not exist" esac done
1.7case实现系统管理工具箱
#!/bin/bash menu(){ cat <<-EOF +------------------------------------------------------------+ | 系统工具箱 | | h.help | | b.磁盘分区情况 | | d.磁盘使用情况 | | m.内存使用情况 | | u.系统负载情况 | | t.CPU使用情况 | | q.exit | +------------------------------------------------------------+ EOF } clear while : do menu echo -en "\e[33m Please choose to use tool: \e[0m" read tools case $tools in h) echo "这是一个系统管理工具箱，可以根据所需选择对应的工具" menu ;; b) lsblk ;; d) df -hT ;; m) free -g ;; u) uptime ;; t) top ;; q) exit ;; "") ;; *) echo -e "\e[31m error option \e[0m" esac done
