shell脚本之case的用法及示例

case基础语法

​ 和if很像

case 变量名4 in
        模式匹配1)
                命令的集合
                ;;
        模式匹配2)
                命令的集合
                ;;
        模式匹配3)
                命令的集合
                ;;
        *)  *的下一行不需要有;;
                echo USAGE[$0 1|2|3]
esac
[root@web scripts]# cat case.sh 
#!/bin/sh
case $1 in
        Linux)
                echo linux......
                ;;
        Shell)
                echo Shell......
                ;;
        MySQL)
                echo MySQL.....
                ;;
        *)
                echo "USAGE $0 [Linux|Shell|MySQL]"
esac

case 批量删除用户

[root@web scripts]# cat casedel.sh
#!/bin/sh
read -p "请输入用户名前缀: " prefix
read -p "请输入要删除几个用户: " num
for i in `seq $num`
do
        echo $prefix$i
done
read -p "你确定要删除以上用户吗?[y|yes|YES|n|N|no]" ready

for n in `seq $num`
do
        name=$prefix$n
        case $ready in
        y|yes|YES)
                id $name &>/dev/null
                if [ $? -eq 0 ];then
                        userdel -r $name
                        [ $? -eq 0 ] && echo "$name del is ok"
                else
                        echo "id: $name: no such user"
                fi
                ;;
        n|N|no)
                echo "不删除我玩啥呢?" && exit
                ;;
        *)
                echo "USAGE $0 [y|yes|YES|n|N|no]"
        esac
done

case案例实现

---

案例一：使用case实现nginx服务启停脚本。

[root@manager case]# cat case-4.sh
#!/bin/bash
# Author:      Oldux.com QQ: 552408925
# Date：       2019-10-30
# FileName：   case-4.sh
# URL:         https://www.xuliangwei.com
# Description： 
source /etc/init.d/functions
nginx_pid=/var/run/nginx.pid


case $1 in
	start)
		if [ -f $nginx_pid ];then
			if [ -s $nginx_pid ];then
				action "Nginx 已经启动" /bin/false
			else
				rm -f $nginx_pid
				systemctl start nginx &>/dev/null
				if [ $? -eq 0 ];then
					action "Nginx启动成功" /bin/true
				else
					action "Nginx启动失败" /bin/false
				fi
			fi
		else
			systemctl start nginx &>/dev/null
			if [ $? -eq 0 ];then
				action "Nginx启动成功" /bin/true
			else
				action "Nginx启动失败" /bin/false
			fi
		fi
		;;
	stop)
		if [ -f $nginx_pid ];then
			systemctl stop nginx && \
			rm -f $nginx_pid
			action "Nginx is stopped" /bin/true
		else
			echo "[error] open() "$nginx_pid" failed (2: No such file or directory)"
		fi
		;;
	status)
		if [ -f $nginx_pid ];then
			echo "nginx (pid  $(cat $nginx_pid)) is running..."
		else
			echo "nginx is stopped"
		fi
		;;
	reload)
		echo "reload"
		;;
	*)
		echo "USAGE:  $0 {start|stop|status|restart}"
		exit 1
esac
[root@manager case]# 

案例二：使用case实现nginx状态监控脚本。 stub_status

---

[root@manager case]# cat case-5.sh 
#!/bin/bash                                                                                      
#********************************************************************
#Author:               一个shell小白
#QQ：                  2226823216
#Date：                2019-10-30
#FileName：            case-5.sh

HostName=test.oldxu.com
Nginx_status_file=nginx.status
Nginx_Status_Path=nginx_status

curl -sH Host:${HostName} http://127.0.0.1/${Nginx_Status_Path} >${Nginx_status_file}
i
case $1 in
	active)
		echo $(( $(awk '/Active connections/ {print $NF}' ${Nginx_status_file}) -1 ))
		;;
	accepts)
		echo $(( $(awk 'NR==3 {print $1}' ${Nginx_status_file}) -1 ))
		;;
	handled)
		echo $(( $(awk 'NR==3 {print $2}' ${Nginx_status_file}) -1 ))
		;;

	requests)
		echo $(( $(awk 'NR==3 {print $3}' ${Nginx_status_file}) -1 ))
		;;
	Reading)
		echo $(( $(awk 'NR==4 {print $2}' ${Nginx_status_file}) ))
		;;

	Writing)
		echo $(( $(awk 'NR==4 {print $4}' ${Nginx_status_file}) ))
		;;

	Waiting)
		echo $(( $(awk 'NR==4 {print $6}' ${Nginx_status_file}) ))
		;;

	*)
		echo "USAGE: $0 { active | accepts | handled | requests | Reading  | Writing  | Waiting }"
		exit 1
esac

案例三：需求3：使用case实现php-fpm状态监控脚本。

[root@web01 php-fpm.d]# cd /etc/php-fpm.d/
[root@web01 php-fpm.d]# ls
www.conf
[root@web01 php-fpm.d]# vim www.conf 
添加如下一行代码
pm.status_path = /php_fpm_status
[root@web01 php-fpm.d]# systemctl restart php-fpm
[root@web01 conf.d]# cat oldxu.com.conf 
server {
	listen 80;
	server_name test.oldxu.com;

	location / {
		index index.heml;
	
	}
	location /nginx_status {
		stub_status;
		}
	location /php_fpm_status {
	fastcgi_pass 127.0.0.1:9000;
	fastcgi_index index.php;
	fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
	include fastcgi_params;

}
}
[root@web01 conf.d]# curl -sH Host:test.oldxu.com http://127.0.0.1:80/php_fpm_status
pool:                 www
process manager:      dynamic
start time:           30/Oct/2019:21:37:59 +0800
start since:          79
accepted conn:        1
listen queue:         0
max listen queue:     0
listen queue len:     128
idle processes:       4
active processes:     1
total processes:      5
max active processes: 1
max children reached: 0
slow requests:        0

[root@web01 case]# cat var01.sh 
#!/bin/bash 
Hostname=test.oldxu.com
Php_status=php_fpm_status
Php_backss=Php_backss
curl -sH Host:${Hostname} http://127.0.0.1:80/${Php_status} >${Php_backss}
case $1 in
	pool)
		echo $(( $(awk 'NR==1 {print $NF}' ${Php_backss}) ))
		;;
	listenqueuelen)
		echo $(( $(awk 'NR==8 {print $NF}' ${Php_backss}) ))
		;;
	*)
		echo "USAGE: $0 {pool |  listenqueuelen}"
		exit 
esac