详解shell脚本中的case条件语句介绍和使用案例

 case "变量" in 值1) 指令1... ;; 值2) 指令2... ;; *） 指令3... esac

 case "找工作条件" in 给的钱多) 给你工作... ;; 给股份) 给你工作... ;; 有发展前景) 可以试试... ;; *) bye bye !! esac

 [root@shell scripts]# cat num.sh #!/bin/bash #create by guoke #function number input read -p "please input a number：" num #打印信息提示用户输入，输入信息赋值给num变量 case "$num" in 1) echo "The num you input is 1" ;; [2-5]) 　　echo "The num you input is 2-5" ;; [6-9]) 　　echo "The num you input is 6-9" ;; *) 　　echo "please input number[1-9] int" 　　 exit; esac

 [root@shell scripts]# cat menu.sh #!/bin/bash #create by guoke #function print menu RED_COLOR='\E[1;31m' GREEN_COLOR='\E[1;32m' YELLOW_COLOR='\E[1;33m' BLUE_COLOR='\E[1;34m' RES='\E[0m' echo ' #使用echo打印菜单 ############################# 1.banana 2.apple 3.pear 4.cherry ############################# ' read -p "please select a num：" num case "$num" in 1) 　　echo -e "${YELLOW_COLOR} banana ${RES}" ;; 2) 　　echo -e "${RED_COLOR} apple ${RES}" ;; 3) 　　echo -e "${GREEN_COLOR} pear ${RES}" ;; 4) 　　echo -e "${BLUE_COLOR} cherry ${RES}" ;; *) 　　echo "please input {1|2|3|4}" esac

 cat<<-EOF =============================== 1.banana 2.apple 3.pear 4.cherry =============================== EOF

 [root@shell scripts]# sh menu.sh ############################# 1.banana 2.apple 3.pear 4.cherry ############################# please select a num： please input {1|2|3|4} 

 #!/bin/bash yum install gcc pcre pcre-devel wget openssl openssl-devel.x86_64 -y mkdir -p /home/demo/tools cd /home/demo/tools/ wget -q http://nginx.org/download/nginx-1.6.3.tar.gz useradd nginx -s /sbin/nologin -M tar xf nginx-1.6.3.tar.gz cd nginx-1.6.3/ ./configure --user=nginx --group=nginx --prefix=/application/nginx --with-http_stub_status_module --with-http_ssl_module make make install ln -s /application/nginx-1.6.3 /application/nginx/ #做软连接 /application/nginx/sbin/nginx -t #检查语法 /application/nginx/sbin/nginx #启动服务

 [root@shell init.d]# chmod +x /etc/init.d/nginxd [root@shell init.d]# cat nginxd #!/bin/bash #chkconfig: 2345 40 98 #设定2345级别，开机第40位启动脚本，关机第98位关闭脚本 #create by guoke #email:1075792988@qq.com #function nginx start scripts [ -f /etc/init.d/functions ] && source /etc/init.d/functions #引入系统函数库 PIDFILE=/application/nginx/logs/nginx.pid #定义PID文件路径 NGINX=/application/nginx/sbin/nginx #定义启动命令路径 value(){ #定义返回值函数 RETVAL=$? if [ $RETVAL -eq 0 ];then 　　action "Nginx is $1" /bin/true else 　　action "Nginx is $1" /bin/true fi } start(){ #定义启动函数 if [ -f $PIDFILE ];then #判断PIDFILE存不存在，存在就打印运行，否则就启动 　　echo "Nginx is running" else 　　$NGINX 　　value start #调用返回值函数 fi } stop(){ #定义停止函数 if [ ! -f $PIDFILE ];then #也是通过判断PID文件是否存在然后进行相关操作 　　echo "Nginx not running" else 　　$NGINX -s stop 　　value stop fi } reload(){ #定义重启函数 if [ ! -f $PIDFILE ];then 　　echo "not open $PIDFILE no such directory" else 　　$nginx -s reload 　　value reload fi } case "$1" in #使用case接收脚本传参的字符串 start) #如果第一个参数为start，调用start函数 　　start ;; stop) #如果第一个参数为stop，调用stop函数 　　stop ;; reload) 　　stop 　　sleep 1 　　start ;; *) 　　echo "USAGE:$0 {stop|start|reload}" 　　exit 1 esac

 [demo@shell ~]$ ssh-keygen -t dsa -P "" -f ~/.ssh/id_dsa Generating public/private dsa key pair. Enter file in which to save the key (/home/demo/.ssh/id_dsa): Created directory '/home/demo/.ssh'. Your identification has been saved in /home/demo/.ssh/id_dsa. Your public key has been saved in /home/demo/.ssh/id_dsa.pub. The key fingerprint is: SHA256:BTFfcC2hMKBzuZeUYylC3qgza7z4X6j3RBlwq8Beoak demo@shell The key's randomart image is: +---[DSA 1024]----+ | + o.*...+o | | . = B o O +. . | | = B B * + . | | o + = B + | |E = . + S | | . + o .  | | + . o  | | o o.o  | |..+o...  | +----[SHA256]-----+ #命令说明：一键生成密钥，不用按回车。-t：指定要创建的密钥类型，-P：提供旧密码，空表示不需要密码，-f：指定位置 #将公钥拷贝到其他服务器的demo用户 [demo@shell ~]$ ssh-copy-id -i .ssh/id_dsa.pub "demo@192.168.86.129" [demo@shell ~]$ ssh-copy-id -i .ssh/id_dsa.pub "demo@192.168.86.130" [demo@shell ~]$ ssh-copy-id -i .ssh/id_dsa.pub demo@192.168.86.131

 [root@shell scripts]# cat tiaobanji.sh #!/bin/bash trapper(){ #定义屏蔽信号函数 trap '' INT QUIT TSTP TERM HUB } menu(){ #定义菜单列表函数 cat<<-EOF #加-后面的EOF就可以不用顶格 ==============Host List============== 1) 192.168.86.129 2) 192.168.86.130 3) 192.168.86.131 4) 192.168.86.132 5) exit ===================================== EOF } USER=demo host(){ #定义主机列表函数 case "$1" in 1) ssh $USER@192.168.86.129 ;; 2) ssh $USER@192.168.86.130 ;; 3) ssh $USER@192.168.86.131 ;; 4) ssh $USER@192.168.86.132 ;; 5) exit esac } main(){ #定义主函数 while : #while循环，一直循环 do trapper #调用trapper函数 clear #清屏 menu #调用菜单函数 read -p "please select a num：" num #获取用户输入 host $num #调用主机列表函数和传入的参数，进行远程登录 done } main #调用主函数

 [root@shell ~]# cd /etc/profile.d/ [root@shell profile.d]# cat jump.sh #!/bin/bash [ $UID -ne 0 ] && . /scripts/tiaobanji.sh

 ==============Host List============== 1) 192.168.86.129 2) 192.168.86.130 3) 192.168.86.131 4) 192.168.86.132 5) exit ===================================== please select a num：1 #进行选择 Last login: Tue Mar 31 23:48:33 2020 from 192.168.86.128 [demo@mysql ~]$