shell - case 流程控制

Posted 2022-08-22 afrafre

1. case 实现程序流程的选择，循环

# 服务的脚本启动和停止 ---- case 的应用场景
case variables in 
variables 1)
    order 1;;
variables 2）
    order 2;;
variables 3)
    order 3;;
*)
    no matches
esac
# 注意 ｉｆ不能同时判断用户输入为　１　或者是　ｂａｃｋｕｐ　

# 使用case 判断用户输入，注意结尾用 ；；

#!/usr/bin/bash
cat <<eof
####################
1. backup
2. copy
3. quit
####################
eof
read -p "please enter [1|2|3]:" re
case $re in
1|backup)   # 这里可以同时判断输入的是1还是backup , 区别于if 判断
        echo "backup";;
2|copy)
        echo "copy";;
3|quit)
        echo "quit" && exit;;
*)
        echo "attention your input!!!"
        echo "USAGE: $0 1|2|3"
esac

一个rsync 的启动和停止的脚本

# 注意脚本名 不能用rsync , 这样取进程号的时候才不会取出多个
1. 如何启动命令 rsync --daemon
ps aux|grep rsync|grep -v grep
2. 如何停止    pkill rsync
# $$ 当前脚本运行时的进程号

source /etc/init.d/functions
# 传入第一个参数
rs=$1
if [ $rs == 'start' ];then
        if [ ! -f /var/run/rsync.pid ];then
                touch /var/run/rsync.pid
                rsync --daemon
                # 注意使用action ,true 为绿色，false为红色
                action 'rsync is starting' /bin/true
        else
                action 'rsync already started' /bin/false
        fi
elif [ $rs == 'stop' ];then
        if [ ! -f /var/run/rsync.pid ];then
                action 'async is already stopped' /bin/false
        else
                rm -f /var/run/rsync.pid
                pkill rsync
                action 'rsync is stopping' /bin/true
        fi
elif [ $rs == 'status' ];then
    if [ ! -f /var/run/rsync.pid ];then
        echo 'Rsync service status inactive'
    else
        echo $$
        rsync_pid=$$
        rsync_status=$(ps aux|grep rsync|grep -v grep|grep -v $rsync_pid|awk 'print $2')
        echo 'rsync service status active $rsync_status'
    fi
else
        echo 'USAGE: $0 start|stop'
        exit
fi
###################### 使用case 来完成服务的启动和停止 ################################

#!/usr/bin/bash
source /etc/init.d/functions
rs=$1
case $rs in 
    start)
        #先判断文件是否存在
        if [ ! -f /var/run/rsync.pid ];then
            touch /var/run/rsync.pid
            rsync --daemon
            action "rsync starting..." /bin/true
        else
            action "rsync already started" /bin/false
        fi  
        ;;
    stop)
        # 文件如果不存在已经停了
        if [ ! -f /var/run/rsync.pid ];then
            action "rsync is already stopped" /bin/false
        else
            action "rsync is stopping" /bin/true
            rm -f /var/run/rsync.pid
            pkill rsync
        fi
        ;;
    status)
        echo "enter status"
        # 判断文件存在的话输出pid
        if [ ! -f /var/run/rsync.pid ];then
            echo " rsync service status inactive"
        else
            Rsync_status=$(ps aux|grep rsync|grep -v grep|awk 'print $2')
            # 注意 不能单引号套双引号，这样$Rsync_status 原样输出
            echo "rsync service status active  '$Rsync_status' " 
        fi
        ;;
    *)
        echo "USAGE $0 start|stop|status"
        exit
esac 

nginx 启动和停止脚本

# 如何启动 /usr/sbin/nginx
# 如何停止 /usr/sbin/nginx -s stop
# 如何重载 /usr/sbin/nginx -s reload

#!/usr/bin/bash
source /etc/init.d/functions
# 要加锁，脚本运行过程中不能重复执行
if [ -f /tmp/nginx.lock ];then
    echo "脚本正在运行，请稍后" 
    exit
fi
touch /tmp/nginx.lock
# 开始正文
rs=$1
case $rs in 
    start)
        if [ -f /var/run/nginx.pid ];then
            action " already started" /bin/false
            exit
        else
            /usr/sbin/nginx
            action " start successfully" /bin/true
        fi
        ;;
    stop)
        if [ -f /var/run/nginx.pid ];then
            /usr/sbin/nginx -s stop
            if [ $? -eq 0 ];then
                action "stop successfully" /bin/true
            else
                action "stop failed" /bin/false
            fi
        else
            action "already stopped" /bin/false
        fi
        ;;
    reload)
        # 如果文件存在，可以重载
        if [ -f /var/run/nginx.pid ];then
            /usr/sbin/nginx -s reload
            if [ $? -eq 0 ];then
                action "reload successly" /bin/true
            else
                action " reload failded" /bin/false
            fi
            exit
        else
            action " service already stopped" /bin/false
        fi
        ;;
    status)
        if [ -f /var/run/nginx.pid ];then
            nginx_pid=$(cat /var/run/nginx.pid)
            echo "nginx $nginx_pid is running"
        else
            echo "nginx is not running "
        fi      
        ;;
    *)
        echo "USAGE: $0 [ start | stop | relaod | status ] "
esac
# 脚本运行结束后解锁
rm -f /tmp/nginx.lock
########################################### 修改版#######################################
#!/usr/bin/bash
source /etc/init.d/functions
# 要加锁，脚本运行过程中不能重复执行
if [ -f /tmp/nginx.lock ];then
    echo "脚本正在运行，请稍后" 
    exit
fi
touch /tmp/nginx.lock
rs=$1
case $rs in 
    start)
        if [ -f /var/run/nginx.pid ];then
            action " already started" /bin/false
            exit
        else
            /usr/sbin/nginx
            action " start successfully" /bin/true
            
        fi
        rm -f /tmp/nginx.lock
        ;;
    stop)
        if [ -f /var/run/nginx.pid ];then
            /usr/sbin/nginx -s stop
            if [ $? -eq 0 ];then
                action "stop successfully" /bin/true
                
            else
                action "stop failed" /bin/false
            fi
        else
            action "already stopped" /bin/false
        fi
        rm -f /tmp/nginx.lock
        ;;
    reload)
        # 如果文件存在，可以重载       
        if [ -f /var/run/nginx.pid ];then
            # 判断命令是否执行有错，如果有错取出错误的行
            /usr/sbin/nginx -t &>/dev/null
            if [ $? -eq 0 ];then
                /usr/sbin/nginx -s reload
                if [ $? -eq 0 ];then
                    action "reload successly" /bin/true
                else
                    action " reload failded" /bin/false
                fi
            else
                /usr/sbin/nginx -t &>err.txt
                nginx_conf=$(awk -F "[: ]" 'NR==1 print $(NF-1)' err.txt)
                nginx_line=$(awk -F "[: ]" 'NR==1 print $(NF)' err.txt)
                reap -p "是否进入配置文件进行修改？" re
                case $re in 
                    y|yes|YES)
                        vim +$nginx_line $nginx_conf
                        ;;
                    n|no|NO)
                        echo "modify manully"
                        exit
                        ;;
                    *)
                        echo "USAGE: $0 y|n"
                esac
            fi

            exit
        else
            action " service already stopped" /bin/false
        fi
        rm -f /tmp/nginx.lcok
        ;;
    status)
        if [ -f /var/run/nginx.pid ];then
            nginx_pid=$(cat /var/run/nginx.pid)
            echo "nginx $nginx_pid is running"
        else
            echo "nginx is not running "
        fi
        rm -f /tmp/nginx.lock
        ;;
    *)
        echo "USAGE: $0 [ start | stop | relaod | status ] "
esac
# 脚本运行结束后解锁
rm -f /tmp/nginx.lock

系统管理工具箱

case 实行简单的JumpServer

1. 执行脚本后，需要看到所有能管理的主机
2. 选择菜单，提示输入连接某个主机

#!/usr/bin/bash

# 定义一个函数可以调用多次
meminfo()
    cat <<-EOF
    ******************
    1. lb01-172.16.1.5
    2. lb02-172.16.1.6
    3. web01-172.16.1.8
    h. help
    ******************
    EOF

meminfo
trap "" HUP INT TSTP   # ctrl c v不起作用
read -p "please enter the number you want: " connection
case $connection in 
    1)
        ssh root@lb01-172.16.1.5
        ;;
    2)
        ssh root@lb02-172.16.1.6
        ;;
    3)
        ssh root@web01-172.16.1.8
        ;;
    h)
        clear
        meminfo
        ;;
    *)
        echo "USAGE: $0 输入 1,2,3，h"
esac
'''
可以加死循环，保证程序连接后端服务，退出后还能选择主机
可以将脚本加入到 /etc/bashrc中，用户一连接，就自动运行该脚本
'''

命令总结：
# 创建用户
useradd octivia
# 设置密码
echo "123"|passwd --stdin octivia

多级菜单

# 函数调用
#!/usr/bin/bash
installfunc()
cat <<-EOF
1. 安装nginx
2. 安装php
3. 退出
EOF

nginxfunc()
cat <<-EOF
1. 安装版本1
2. 安装版本2
3. 清屏
4. 返回上一页面
EOF

phpfunc()
cat <<-EOF
1. 安装版本一
2. 安装版本二
3. 退出
EOF

installfunc

read -p "请选择：" software
case $software in
        1)
               clear
                nginxfunc
                read -p "please choose version: " version
                case $version in
                        1)
                                echo "install nginx version1"
                                ;;
                        2)
                                echo "install nginx version2"
                                ;;
                        3)
                                clear ;;
                        4)
                                installfunc
                esac
                ;;
        2)
                phpfunc
                read -p "please choose version: " version
                case $version in
                        1)
                                echo "install php version1"
                                ;;
                        2)
                                echo "install php version2"
                                ;;
                        3)
                                installfunc
                esac
                ;;
        3)
                exit
esac