实用的小shell脚本

       自己写了一下小的shell实例，虽然很小，但所有的大的程序都是由小的模块堆积起来的，程序员一定要懂得一种脚本的书写。

1.模拟linux登录shell

#/bin/bash
echo -n "login:" 
read name
echo -n "password:"
read passwd
if [ $name = "cht" -a $passwd
= "abc" ];then
echo "the host and password
is right!"
else echo "input is error!"
fi

2.比较两个数大小

#/bin/bash
echo "please enter two number"
read a
read b
if test $a -eq $b
then echo "NO.1 = NO.2"

elif test $a -gt $b
then echo "NO.1 > NO.2"
else echo "NO.1 < NO.2" 
fi

3.查找/root/目录下是否存在该文件

#/bin/bash

echo "enter a file name:"

read a

if test  -e /root/$a 

then echo "the file is exist!"

else echo "the file is not exist!"

fi

4.for循环的使用

#/bin/bash

clear

for num in 1 2 3 4 5 6 7 8 9 10

do

    echo "$num"

done

5.

#/bin/bash

echo "Please enter a user:"

read a

b=$(whoami)

if test $a = $b

then echo "the user is running."

else echo "the user is not running."

fi

6.删除当前目录下大小为0的文件

#/bin/bash

for filename in `ls`

do

    if test -d $filename

    then b=0

    else    

       a=$(ls -l $filename | awk '{ print $5 }')

            if test $a -eq 0

             then rm $filename

             fi

        fi      

done

7.如果/export/um_lpp_source下有文件，那么将其文件系统大小改为3G

 #/bin/bash

while line=`ls /export/um_lpp_source`

do

        if test $line=""

        then  echo "NULL"

             sleep 1

    else echo $line

                chfs -a size=3G /export/um_lpp_source

                 exit 0

        fi

done

 

8.测试IP地址

#/bin/bash

for i in  1 2 3 4 5 6 7 8 9 

do

    echo "the number of $i computer is "

    ping -c 1 192.168.0.$i

done

9.如果test.log的大小大于0，那么将/opt目录下的*.tar.gz文件

 #/bin/sh

a=2

while name="test.log"

do

        sleep 1

        b=$(ls -l $name | awk '{print $5}')

        if test $b -ge $a

        #then echo "OK"

    then `cp /opt/*.tar.gz .`

        exit 0

        fi

done

10.打印读取的内容，为下面的例子做准备

#/bin/bash

while read name

do

echo $name

done

11.从0.sh中读取内容并打印

#/bin/bash

while read line

do

    echo $line

done < 0.sh

12.读取a.c中的内容并做加1运算

#/bin/bash

test -e a.c

while read line

do

    a=$(($line+1))

done < a.c

echo $a

13.普通无参数函数

#/bin/bash

p ()

{

    echo "hello"

}

p

14.给函数传递参数

#/bin/bash

p_num ()

{

    num=$1

    echo $num

}

for n in $@

do

    p_num $n

done

15.创建文件夹

#/bin/bash

while :

do

    echo "please input file's name:"

    read a

    if test -e /root/$a

    then

         echo "the file is existing Please input new file name:"

    else

        mkdir $a

        echo "you aye sussesful!"

        break 

    fi

done

16.获取本机IP地址

#/bin/bash

ifconfig | grep "inet addr:" | awk '{ print $2 }'| sed 's/addr://g'

17.查找最大文件

#/bin/bash

a=0

for  name in *.*

do

     b=$(ls -l $name | awk '{print $5}')

    if test $b -ge $a

    then a=$b

         namemax=$name

     fi

done

echo "the max file is $namemax"

18.查找当前网段内IP用户，重定向到ip.txt文件中

#/bin/bash

a=1

while :

do

    a=$(($a+1))

    if test $a -gt 255

    then break

    else

        echo $(ping -c 1 192.168.0.$a | grep "ttl" | awk '{print $4}'| sed 's/://g')

        ip=$(ping -c 1 192.168.0.$a | grep "ttl" | awk '{print $4}'| sed 's/://g')

        echo $ip >> ip.txt

    fi

done

19.打印当前用户

#/bin/bash

echo "Current User is :"

echo $(ps | grep "$$" | awk '{print $2}')

20.case语句练习

#!/bin/bash

clear

echo "enter a number from 1 to 5:"

read num

case $num in

    1) echo "you enter 1"

    ;;

    2) echo "you enter 2"

    ;;

    3) echo "you enter 3"

    ;;

    4) echo "you enter 4"

    ;;

    5) echo "you enter 5"

    ;;

    *) echo "error"

    ;;

esac

21.yes/no返回不同的结构

#!/bin/bash

clear

echo "enter [y/n]:"

read a

case $a in

    y|Y|Yes|YES) echo "you enter $a"

    ;;

    n|N|NO|no) echo "you enter $a"

    ;;

    *) echo "error"

    ;;

esac

22.内置命令的使用

#/bin/bash

    clear

        echo "Hello, $USER"

        echo

        

        echo "Today 's date id `date`"

        echo

        echo "the user is :"

        who

        echo

        echo "this is `uname -s`"

        echo

        echo "that's all folks! "

23.打印无密码用户

#/bin/bash

echo "No Password User are :"

echo $(cat /etc/shadow | grep "!!" | awk 'BEGIN { FS=":" }{print $1}')

24.

#/bin/bash

    clear

        echo "Hello, $USER"

        echo

        

        echo "Today 's date id `date`"

        echo

        echo "the user is :"

        who

        echo

        echo "this is `uname -s`"

        echo

        echo "that's all folks! "