一些简单shell实例

1.模拟linnux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.查看是否当前用户

#!/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文件拷贝到当前目录下

#!/bin/sh
a=2
while name="test.log"
do
sleep 1
b=$(ls -l $name | awk '{print $5}')
if test $b -gt $a
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 -gt $a
then a=$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/bashclearecho "Hello, $USER"echo "Today 's date id `date`"echo "the user is :"whoecho "this is `uname -s`"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}')

         参考：http://blog.chinaunix.net/uid-28804901-id-3874633.html