Shell实战之函数的高级用法

红太狼 2022-01-20 08:47 209阅读 0赞

## 函数定义和使用 ##

#!/bin/bash
    #实时监控nginx进程的状态
    
    this_pid=$$
    
    while true
        do
        ps -ef | grep nginx | grep -v grep | grep -v $this_pid &> /dev/null
        
        if [ $? -eq 0 ];then
        	echo "Nginx is running well"
        	sleep 3
        else
        	systemctl start nginx
        	echo "Nginx is down,Start it...."
        fi
        done
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## 向函数传递参数 ##

#!/bin/bash
    #计算器
    
    function calcu
    {
    	case $2 in
    		+)
    			echo "`expr $1 + $3`"
    			;;
    		-)
    			echo "`expr $1 - $3`"
    			;;
    		\*)
    			echo "`expr $1 \* $3`"
    			;;
    		/)
    			echo "`expr $1 / $3`"
    			;;
    	esac
    }
    
    calcu $1 $2 $3
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## 函数返回值 ##

#!/bin/bash
    #
    
    this_pid=$$
    
    function is_nginx_running
    {
    	ps -ef | grep nginx | grep -v grep | grep -v $this_pid &> /dev/null
    	if [ $? -eq 0 ];then
    		return
    	else
    		return 1
    	fi
    }
    
    is_nginx_running && echo "Nginx is running" || echo "Nginx is stoped"
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#!/bin/bash
    #
    
    function get_users
    {
    	users=`cat /etc/passwd | cut -d: -f1`
    	echo $users
    }
    
    user_list=`get_users`
    
    index=1
    for u in $user_list
    do
    	echo "The $index user is : $u"
    	index=$(($index+1))
    done
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## 局部变量和全局变量 ##

#!/bin/bash
    #
    
    var1="Hello world"
    
    function test
    {
    	local var2=87
    }
    
    test
    
    echo $var1
    echo $var2
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## 函数库 ##

#!/bin/bash
    #
    
    . /root/lesson/3.5/lib/base_function
    
    add 12 23
    
    reduce 90 30
    
    multiple 12 12
    
    divide 12 2
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function add
    {
    	echo "`expr $1 + $2`"
    }
    
    function reduce
    {
    	echo "`expr $1 - $2`"
    }
    
    function multiple
    {
    	echo "`expr $1 \* $2`"
    }
    
    function divide
    {
    	echo "`expr $1 / $2`"
    }
    
    function sys_load
    {
    	echo "Memory Info"
    	echo
    	free -m
    	echo
    	
    	echo "Disk Usage"
    	echo
    	df -h
    	echo
    }
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