Shell编程学习笔记

1.检测某一网段中可达主机，并通过自动回答脚本实现ssh远程连接获取连接到主机名称

程序脚本

#!/bin/bash
#################################################
# Author :Lockey  
# Email  :[e-mail]  
# Version  :v1.1.1 
# Create_date  : 2017-08-22
# Description  : ip test shell script
#################################################
#function to show usage
#用户输入不符合程序参数要求时输出用法示例
function print_usage {
cat << EOF

This utility can detect host reachability!

Usage: ./testip ipstart ipend zone

eg: ./testip 0 255 172.25.254
EOF
echo -e "\n"
}
#function to test the ip reachability
function testIp {
        for((i=$1;i<=$2;i++))
        do
        ip=$3.$i
        ping -c1 -w1 $ip &>/dev/null
        #ping网段内主机，根据命令执行返回值来确定下一步的动作
        if [ $? -eq 0 ]
        then
                result=`/root/useradd/answer.exp $ip redhat hostname | grep foundation | cut -d . -f 1-3`
                #执行自动应答脚本根据命令执行结果处理输出
                echo $result | grep foundation &>/dev/null
                if [ $? -ne 0 ]
                then
                        echo "ssh connection refused  by host $ip"
                else
                        echo "$ip's hostname is: $result"
                fi
        else
                echo "$ip can not be reached!"
        fi
        done
}
print_usage
read -p "Please input startip endip and zone: " ipstart ipend ipzone
#函数调用
testIp $ipstart $ipend $ipzone

expect自动应答脚本

#!/usr/bin/expect
set timeout 3
set num     [ lindex $argv 0 ]
set passwd  [ lindex $argv 1 ]
set com     [ lindex $argv 2 ]
spawn ssh [e-mail]$num $com
#监控执行命令
#spawn scp /root/useradd/lockey-scp-loop.sh [e-mail]$num:/home/kiosk/Desktop
expect {
    "authenticity" { send "yes\r";exp_continue }
    "password"  { send "$passwd\r" }
}
expect eof
#interact

2. 通过脚本导入文件数据批量添加用户、删除用户或者修改用户密码

#!/bin/bash
#################################################
# Author :Lockey  
# Email  :[e-mail]  
# Version  :v1.1.1 
# Create_date  : 2017-08-22
# Description  : user management shell script
#################################################

###function to conduct user add by matched user file and passwd file
function Useradd {
if [ $userNum -ne $passwdNum ]
then
        echo 'User number are not match the passwords line!'
else
        count=1
        for user in `cat $user_file`
        do
                id $user &>/dev/null
                if [ $? -ne 0 ]
                then
                        useradd $user
                        echo "$user successfully created!"
                        password=`sed -n "${count}p" $passwd_file`
                        count=$[ $count + 1 ]
passwd $user &>/dev/null<<end
$password
$password
end

                else
            if [ ! -e $modify_passwd ]
            then
                echo -e "User \033[31m$user\033[0m existed!"
                password=`sed -n "${count}p" $passwd_file`
                            count=$[ $count + 1 ]
passwd $user &>/dev/null <<end
$password
$password
end
    echo -e $user\'s password has been changed!"\n"
            else
                echo -e "User \033[31m$user\033[0m existed!"
            fi
                fi
        done
fi
}

###function to conduct user delete by given user file
function Userdel {
    for user in `cat $user_file`
        do
                userdel -r $user &>/dev/null
                if [ $? -ne 0 ]
                then
                        echo $user does not exist!

                else
                        echo "$user successfully deleted!"
                fi
        done
}

###actions to judge if the given options are reasonable
if [ -z $1 ]
then
        echo 'Please point out your action ( add|delete )!'
        exit 1
fi
action=$1
if [ $action != "delete" ] && [ $action != "add" ]
then
    echo 'Wrong action! add or delete should be specified!'
    exit 1
elif [ -z $2 ]
then
        echo 'Please input user file!'
        exit 1
elif [ -z $3 ] && [ $action = 'add' ]
then
        echo 'Please input passwd file!'
        exit 1
elif [ ! -e $2 ]
then
        echo 'User file not exist!'
        exit 1
elif [ ! -e $3 ] && [ $action = 'add' ]
then
        echo 'Passwd file not exist!'
        exit 1
else
    user_file=$2
    passwd_file=$3
    userNum=`wc -l $user_file | cut -d ' ' -f 1`
    if [ $action = 'delete' ]
    then
        Userdel
    elif [ $action = 'add' ]
    then
        passwdNum=`wc -l $passwd_file | cut -d ' ' -f 1`
        modify_passwd=$4
        Useradd
    else
        echo 'Wrong action!'
    fi
fi

3. 给定秒数然后进行倒计时

#!/bin/bash
read -p "Please input seconds to start the countdown: " times
echo -e 'Time start!\n'
#限定倒计时最长时间为1天，如果不合理则默认为70s
if [ -e $times ] || [ $times -lt 0 ] || [ $times -gt 3600 ]
then
        times=70
fi

m=`expr $times / 60 `
s=`expr $times % 60 `
for(( i=$m; i>=0; i-- ))
do      if [ $i -lt 10 ]
        then
        mm="0${i}"
        else
        mm=$i
        fi
        for(( j=$s; j>=0; j-- ))
        do
                if [ $j -lt 10 ]
                then
                ss="0${j}"
                else
                ss=$j
                fi
                echo -n -----------------Time left: '***' $mm:$ss '***'-------------------
        echo -ne "\r    \r"
                sleep 1
        done
        s=59
done
clear
echo 'Time over!'

4. 单行或者多行字符反转

!/bin/bash
for arg in [e-mail]
do
    inputstr=$arg
    len=${#inputstr}
    for((i=1;i<=$len;i++))
    do
        echo -n ${inputstr:0-$i:1}
        #字符从右切片，每次左移一位取一个字符
    done
    echo ""
done